diff --git a/include/verilated.cpp b/include/verilated.cpp
index 6329831c7..663b56881 100644
--- a/include/verilated.cpp
+++ b/include/verilated.cpp
@@ -23,8 +23,7 @@
 //=========================================================================
 
 #include "verilated.h"
-#include <string.h>
-#include <ctype.h>
+#include <cctype>
 
 #define VL_VALUE_STRING_MAX_WIDTH 1024	///< Max static char array for VL_VALUE_STRING
 
diff --git a/include/verilated.h b/include/verilated.h
index 8f6dc2357..b53c390d8 100644
--- a/include/verilated.h
+++ b/include/verilated.h
@@ -29,11 +29,11 @@
 
 #include "verilatedos.h"
 
-#include <assert.h>
-#include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
+#include <cassert>
+#include <cstdarg>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
 #include <iostream>
 using namespace std;
 
diff --git a/src/V3Active.cpp b/src/V3Active.cpp
index 8b62e2cfa..7cb768d6e 100644
--- a/src/V3Active.cpp
+++ b/src/V3Active.cpp
@@ -32,8 +32,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <algorithm>
diff --git a/src/V3ActiveTop.cpp b/src/V3ActiveTop.cpp
index fe534e24f..c957dccfe 100644
--- a/src/V3ActiveTop.cpp
+++ b/src/V3ActiveTop.cpp
@@ -29,8 +29,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3Assert.cpp b/src/V3Assert.cpp
index 993c33adb..3dcbb7643 100644
--- a/src/V3Assert.cpp
+++ b/src/V3Assert.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <iomanip>
diff --git a/src/V3AssertPre.cpp b/src/V3AssertPre.cpp
index f1e37b0f7..9b580c666 100644
--- a/src/V3AssertPre.cpp
+++ b/src/V3AssertPre.cpp
@@ -23,8 +23,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <iomanip>
diff --git a/src/V3Ast.cpp b/src/V3Ast.cpp
index 4e1b8e62c..0e22a0746 100644
--- a/src/V3Ast.cpp
+++ b/src/V3Ast.cpp
@@ -18,8 +18,8 @@
 //
 //*************************************************************************
 
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <fstream>
 #include <iomanip>
 #include <memory>
diff --git a/src/V3AstNodes.cpp b/src/V3AstNodes.cpp
index 94385e511..a950496f9 100644
--- a/src/V3AstNodes.cpp
+++ b/src/V3AstNodes.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <fstream>
 #include <iomanip>
 #include <vector>
diff --git a/src/V3Begin.cpp b/src/V3Begin.cpp
index 61d409aca..85f716d13 100644
--- a/src/V3Begin.cpp
+++ b/src/V3Begin.cpp
@@ -28,8 +28,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <cstring>
 #include <algorithm>
diff --git a/src/V3Branch.cpp b/src/V3Branch.cpp
index ebc780e02..d7f826be9 100644
--- a/src/V3Branch.cpp
+++ b/src/V3Branch.cpp
@@ -26,8 +26,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 
diff --git a/src/V3Broken.cpp b/src/V3Broken.cpp
index c07aa5d53..fea5a91c7 100644
--- a/src/V3Broken.cpp
+++ b/src/V3Broken.cpp
@@ -27,8 +27,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <map>
diff --git a/src/V3Case.cpp b/src/V3Case.cpp
index 5b8c8436c..4e5abc72f 100644
--- a/src/V3Case.cpp
+++ b/src/V3Case.cpp
@@ -39,8 +39,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Cast.cpp b/src/V3Cast.cpp
index 22c1ab2ef..5c1c2d243 100644
--- a/src/V3Cast.cpp
+++ b/src/V3Cast.cpp
@@ -43,8 +43,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Changed.cpp b/src/V3Changed.cpp
index b06bf2b45..8116ff8af 100644
--- a/src/V3Changed.cpp
+++ b/src/V3Changed.cpp
@@ -32,8 +32,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <set>
diff --git a/src/V3Clean.cpp b/src/V3Clean.cpp
index 4c9600ea3..0d0d5e76d 100644
--- a/src/V3Clean.cpp
+++ b/src/V3Clean.cpp
@@ -29,8 +29,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Clock.cpp b/src/V3Clock.cpp
index 1d6dd82d5..23a66a8c6 100644
--- a/src/V3Clock.cpp
+++ b/src/V3Clock.cpp
@@ -33,8 +33,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Combine.cpp b/src/V3Combine.cpp
index b63d73296..ff0fb9b24 100644
--- a/src/V3Combine.cpp
+++ b/src/V3Combine.cpp
@@ -36,8 +36,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3Const.cpp b/src/V3Const.cpp
index d14155604..7d6eab5e7 100644
--- a/src/V3Const.cpp
+++ b/src/V3Const.cpp
@@ -26,8 +26,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 
diff --git a/src/V3Coverage.cpp b/src/V3Coverage.cpp
index 0c6d2a4f1..6544157d3 100644
--- a/src/V3Coverage.cpp
+++ b/src/V3Coverage.cpp
@@ -30,8 +30,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 
diff --git a/src/V3Dead.cpp b/src/V3Dead.cpp
index acdfcbdac..81f16ab63 100644
--- a/src/V3Dead.cpp
+++ b/src/V3Dead.cpp
@@ -25,8 +25,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <vector>
 #include <map>
diff --git a/src/V3Delayed.cpp b/src/V3Delayed.cpp
index 3202bd486..774c02c84 100644
--- a/src/V3Delayed.cpp
+++ b/src/V3Delayed.cpp
@@ -53,8 +53,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <map>
diff --git a/src/V3Depth.cpp b/src/V3Depth.cpp
index 0e4348e20..f2455bee7 100644
--- a/src/V3Depth.cpp
+++ b/src/V3Depth.cpp
@@ -29,8 +29,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3DepthBlock.cpp b/src/V3DepthBlock.cpp
index d052d1cb9..0ef77ed0f 100644
--- a/src/V3DepthBlock.cpp
+++ b/src/V3DepthBlock.cpp
@@ -26,8 +26,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Descope.cpp b/src/V3Descope.cpp
index f3c84c83a..42753db40 100644
--- a/src/V3Descope.cpp
+++ b/src/V3Descope.cpp
@@ -28,8 +28,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 
diff --git a/src/V3EmitC.cpp b/src/V3EmitC.cpp
index f9ebab70c..ca1c20d83 100644
--- a/src/V3EmitC.cpp
+++ b/src/V3EmitC.cpp
@@ -20,10 +20,10 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
-#include <math.h>
+#include <cmath>
 #include <map>
 #include <vector>
 #include <algorithm>
diff --git a/src/V3EmitCBase.h b/src/V3EmitCBase.h
index 425424555..55aeb323a 100644
--- a/src/V3EmitCBase.h
+++ b/src/V3EmitCBase.h
@@ -24,10 +24,10 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
-#include <math.h>
+#include <cmath>
 
 #include "V3Global.h"
 #include "V3File.h"
diff --git a/src/V3EmitCInlines.cpp b/src/V3EmitCInlines.cpp
index b7b8610c3..41ce2d1e0 100644
--- a/src/V3EmitCInlines.cpp
+++ b/src/V3EmitCInlines.cpp
@@ -20,10 +20,10 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
-#include <math.h>
+#include <cmath>
 #include <map>
 #include <vector>
 
diff --git a/src/V3EmitCSyms.cpp b/src/V3EmitCSyms.cpp
index d6a291a7c..bce113335 100644
--- a/src/V3EmitCSyms.cpp
+++ b/src/V3EmitCSyms.cpp
@@ -20,10 +20,10 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
-#include <math.h>
+#include <cmath>
 #include <map>
 #include <set>
 #include <vector>
diff --git a/src/V3EmitMk.cpp b/src/V3EmitMk.cpp
index dd03c3650..b7bf3df0d 100644
--- a/src/V3EmitMk.cpp
+++ b/src/V3EmitMk.cpp
@@ -20,10 +20,10 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
-#include <math.h>
+#include <cmath>
 #include <map>
 #include <vector>
 #include <algorithm>
diff --git a/src/V3EmitV.cpp b/src/V3EmitV.cpp
index bb0c27c31..a6936dffb 100644
--- a/src/V3EmitV.cpp
+++ b/src/V3EmitV.cpp
@@ -20,10 +20,10 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
-#include <math.h>
+#include <cmath>
 #include <map>
 #include <vector>
 #include <algorithm>
diff --git a/src/V3Error.cpp b/src/V3Error.cpp
index d24f0f2f8..8fe7ed9ad 100644
--- a/src/V3Error.cpp
+++ b/src/V3Error.cpp
@@ -18,8 +18,8 @@
 //
 //*************************************************************************
 
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <cstring>
 #include <set>
 #include "V3Error.h"
diff --git a/src/V3Expand.cpp b/src/V3Expand.cpp
index 6637bc9f8..0c8441018 100644
--- a/src/V3Expand.cpp
+++ b/src/V3Expand.cpp
@@ -31,8 +31,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3File.cpp b/src/V3File.cpp
index 5dfcd4633..f288c76c9 100644
--- a/src/V3File.cpp
+++ b/src/V3File.cpp
@@ -20,7 +20,7 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdarg.h>
+#include <cstdarg>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
diff --git a/src/V3File.h b/src/V3File.h
index d758d10d3..c0783d3b0 100644
--- a/src/V3File.h
+++ b/src/V3File.h
@@ -24,7 +24,7 @@
 #include "config_build.h"
 #include "verilatedos.h"
 #include "V3Error.h"
-#include <stdio.h>
+#include <cstdio>
 #include <stack>
 #include <set>
 #include <fstream>
diff --git a/src/V3Gate.cpp b/src/V3Gate.cpp
index 8d9588615..845110b16 100644
--- a/src/V3Gate.cpp
+++ b/src/V3Gate.cpp
@@ -27,8 +27,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <iomanip>
diff --git a/src/V3GenClk.cpp b/src/V3GenClk.cpp
index 4fa77374e..677a21597 100644
--- a/src/V3GenClk.cpp
+++ b/src/V3GenClk.cpp
@@ -25,8 +25,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 
 #include "V3Global.h"
diff --git a/src/V3Graph.cpp b/src/V3Graph.cpp
index 5d984651f..5a9c5adb1 100644
--- a/src/V3Graph.cpp
+++ b/src/V3Graph.cpp
@@ -21,8 +21,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3GraphAcyc.cpp b/src/V3GraphAcyc.cpp
index ea8f0ac06..e0ca48227 100644
--- a/src/V3GraphAcyc.cpp
+++ b/src/V3GraphAcyc.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3GraphAlg.cpp b/src/V3GraphAlg.cpp
index 7854316f4..996605716 100644
--- a/src/V3GraphAlg.cpp
+++ b/src/V3GraphAlg.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3GraphDfa.cpp b/src/V3GraphDfa.cpp
index b00e5572b..3bf5c2540 100644
--- a/src/V3GraphDfa.cpp
+++ b/src/V3GraphDfa.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <stack>
 #include <map>
diff --git a/src/V3GraphTest.cpp b/src/V3GraphTest.cpp
index 8ea890959..149589fed 100644
--- a/src/V3GraphTest.cpp
+++ b/src/V3GraphTest.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 
 #include "V3Global.h"
diff --git a/src/V3Hashed.cpp b/src/V3Hashed.cpp
index bdd656195..dfeaed8e0 100644
--- a/src/V3Hashed.cpp
+++ b/src/V3Hashed.cpp
@@ -27,8 +27,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Inline.cpp b/src/V3Inline.cpp
index 1231251aa..a0314e143 100644
--- a/src/V3Inline.cpp
+++ b/src/V3Inline.cpp
@@ -30,8 +30,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3Inst.cpp b/src/V3Inst.cpp
index 500db955a..7400625fb 100644
--- a/src/V3Inst.cpp
+++ b/src/V3Inst.cpp
@@ -27,8 +27,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Life.cpp b/src/V3Life.cpp
index 39c8acb2c..f3f53191b 100644
--- a/src/V3Life.cpp
+++ b/src/V3Life.cpp
@@ -29,8 +29,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 
diff --git a/src/V3LifePost.cpp b/src/V3LifePost.cpp
index 38c6c969d..d9e5d75c6 100644
--- a/src/V3LifePost.cpp
+++ b/src/V3LifePost.cpp
@@ -30,8 +30,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 
 #include "V3Global.h"
diff --git a/src/V3Link.cpp b/src/V3Link.cpp
index 8c5a547bb..f159c0479 100644
--- a/src/V3Link.cpp
+++ b/src/V3Link.cpp
@@ -27,8 +27,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <algorithm>
diff --git a/src/V3LinkCells.cpp b/src/V3LinkCells.cpp
index 7ed428a8a..4975a541c 100644
--- a/src/V3LinkCells.cpp
+++ b/src/V3LinkCells.cpp
@@ -26,8 +26,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <algorithm>
diff --git a/src/V3LinkDot.cpp b/src/V3LinkDot.cpp
index 604aed677..d235cbeb7 100644
--- a/src/V3LinkDot.cpp
+++ b/src/V3LinkDot.cpp
@@ -30,8 +30,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <cstring>
 #include <unistd.h>
 #include <map>
diff --git a/src/V3LinkLValue.cpp b/src/V3LinkLValue.cpp
index 22e0db4f3..40281a7e2 100644
--- a/src/V3LinkLValue.cpp
+++ b/src/V3LinkLValue.cpp
@@ -24,8 +24,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <algorithm>
diff --git a/src/V3LinkLevel.cpp b/src/V3LinkLevel.cpp
index 6dc298fe3..646ddb2c4 100644
--- a/src/V3LinkLevel.cpp
+++ b/src/V3LinkLevel.cpp
@@ -25,8 +25,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <algorithm>
diff --git a/src/V3LinkParse.cpp b/src/V3LinkParse.cpp
index 321036dba..b13969da3 100644
--- a/src/V3LinkParse.cpp
+++ b/src/V3LinkParse.cpp
@@ -28,8 +28,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <algorithm>
diff --git a/src/V3LinkResolve.cpp b/src/V3LinkResolve.cpp
index 436de9b3b..fd6e9d7b8 100644
--- a/src/V3LinkResolve.cpp
+++ b/src/V3LinkResolve.cpp
@@ -29,8 +29,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <algorithm>
diff --git a/src/V3Localize.cpp b/src/V3Localize.cpp
index a59c4d282..d08248d67 100644
--- a/src/V3Localize.cpp
+++ b/src/V3Localize.cpp
@@ -28,8 +28,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <vector>
 
diff --git a/src/V3Name.cpp b/src/V3Name.cpp
index a09aa6a0b..2c26c19f3 100644
--- a/src/V3Name.cpp
+++ b/src/V3Name.cpp
@@ -25,8 +25,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Number.cpp b/src/V3Number.cpp
index 4cdb33b67..9efd66630 100644
--- a/src/V3Number.cpp
+++ b/src/V3Number.cpp
@@ -20,9 +20,9 @@
 
 #include <config_build.h>
 #include "verilatedos.h"
-#include <math.h>
-#include <stdio.h>
-#include <stdarg.h>
+#include <cmath>
+#include <cstdio>
+#include <cstdarg>
 #include <cstring>
 #include <algorithm>
 #include "V3Number.h"
diff --git a/src/V3Number_test.cpp b/src/V3Number_test.cpp
index c73004be6..643418c38 100644
--- a/src/V3Number_test.cpp
+++ b/src/V3Number_test.cpp
@@ -26,8 +26,8 @@
 
 #include <config_build.h>
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <algorithm>
 #include "V3Number.h"
 
diff --git a/src/V3Order.cpp b/src/V3Order.cpp
index a45cfcfdd..8440bc2f0 100644
--- a/src/V3Order.cpp
+++ b/src/V3Order.cpp
@@ -88,8 +88,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3Param.cpp b/src/V3Param.cpp
index fb42d7be1..fd66bee88 100644
--- a/src/V3Param.cpp
+++ b/src/V3Param.cpp
@@ -30,8 +30,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <vector>
diff --git a/src/V3PreProc.cpp b/src/V3PreProc.cpp
index 65e22fe18..f538769b4 100644
--- a/src/V3PreProc.cpp
+++ b/src/V3PreProc.cpp
@@ -21,8 +21,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <fstream>
 #include <stack>
diff --git a/src/V3PreShell.cpp b/src/V3PreShell.cpp
index 8c37ad86c..74f0a6e91 100644
--- a/src/V3PreShell.cpp
+++ b/src/V3PreShell.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <iostream>
 #include <algorithm>
diff --git a/src/V3Premit.cpp b/src/V3Premit.cpp
index 7bf8e6301..c06db3532 100644
--- a/src/V3Premit.cpp
+++ b/src/V3Premit.cpp
@@ -27,8 +27,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <list>
diff --git a/src/V3Read.cpp b/src/V3Read.cpp
index 98db6fa91..fbdd191ee 100644
--- a/src/V3Read.cpp
+++ b/src/V3Read.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <fstream>
 
diff --git a/src/V3Scope.cpp b/src/V3Scope.cpp
index 220606854..9e0f066e2 100644
--- a/src/V3Scope.cpp
+++ b/src/V3Scope.cpp
@@ -27,8 +27,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <iomanip>
diff --git a/src/V3SenTree.h b/src/V3SenTree.h
index 87c61e820..6a9c04145 100644
--- a/src/V3SenTree.h
+++ b/src/V3SenTree.h
@@ -36,8 +36,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <algorithm>
diff --git a/src/V3Signed.cpp b/src/V3Signed.cpp
index 1d903975e..86d7d7265 100644
--- a/src/V3Signed.cpp
+++ b/src/V3Signed.cpp
@@ -30,8 +30,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <iomanip>
diff --git a/src/V3Split.cpp b/src/V3Split.cpp
index 58f6d1e4b..91787a111 100644
--- a/src/V3Split.cpp
+++ b/src/V3Split.cpp
@@ -51,8 +51,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3SplitAs.cpp b/src/V3SplitAs.cpp
index b8472e1a8..1fa2125af 100644
--- a/src/V3SplitAs.cpp
+++ b/src/V3SplitAs.cpp
@@ -27,8 +27,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3Stats.cpp b/src/V3Stats.cpp
index 9bdbefba1..1ba13e3af 100644
--- a/src/V3Stats.cpp
+++ b/src/V3Stats.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <iomanip>
diff --git a/src/V3StatsReport.cpp b/src/V3StatsReport.cpp
index 1ad59b89f..9afbc9e7f 100644
--- a/src/V3StatsReport.cpp
+++ b/src/V3StatsReport.cpp
@@ -20,8 +20,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 #include <iomanip>
diff --git a/src/V3Subst.cpp b/src/V3Subst.cpp
index ffc2bde2a..f72813ad0 100644
--- a/src/V3Subst.cpp
+++ b/src/V3Subst.cpp
@@ -28,8 +28,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 #include <vector>
diff --git a/src/V3SymTable.h b/src/V3SymTable.h
index dd5c02ea3..097bd6bd8 100644
--- a/src/V3SymTable.h
+++ b/src/V3SymTable.h
@@ -23,8 +23,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 
diff --git a/src/V3Table.cpp b/src/V3Table.cpp
index d49316332..eaee93a95 100644
--- a/src/V3Table.cpp
+++ b/src/V3Table.cpp
@@ -27,10 +27,10 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
-#include <math.h>
+#include <cmath>
 #include <deque>
 
 #include "V3Global.h"
diff --git a/src/V3Task.cpp b/src/V3Task.cpp
index d23ac1adb..a1ab0307a 100644
--- a/src/V3Task.cpp
+++ b/src/V3Task.cpp
@@ -29,8 +29,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <map>
 
diff --git a/src/V3Trace.cpp b/src/V3Trace.cpp
index e514d9c3d..1b30136aa 100644
--- a/src/V3Trace.cpp
+++ b/src/V3Trace.cpp
@@ -48,8 +48,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <set>
 #include <map>
diff --git a/src/V3TraceDecl.cpp b/src/V3TraceDecl.cpp
index 3f60ffc2d..4b0345f6b 100644
--- a/src/V3TraceDecl.cpp
+++ b/src/V3TraceDecl.cpp
@@ -26,8 +26,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 
 #include "V3Global.h"
diff --git a/src/V3Unknown.cpp b/src/V3Unknown.cpp
index 8724beec8..9f485961b 100644
--- a/src/V3Unknown.cpp
+++ b/src/V3Unknown.cpp
@@ -33,8 +33,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Unroll.cpp b/src/V3Unroll.cpp
index a493b4645..8174cc9c7 100644
--- a/src/V3Unroll.cpp
+++ b/src/V3Unroll.cpp
@@ -30,8 +30,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 #include <algorithm>
 
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index 272b994e3..42f34fc25 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -45,8 +45,8 @@
 
 #include "config_build.h"
 #include "verilatedos.h"
-#include <stdio.h>
-#include <stdarg.h>
+#include <cstdio>
+#include <cstdarg>
 #include <unistd.h>
 
 #include "V3Global.h"
diff --git a/src/config_build.h.in b/src/config_build.h.in
index 5d977a84b..3f99cfe42 100644
--- a/src/config_build.h.in
+++ b/src/config_build.h.in
@@ -83,7 +83,7 @@
 #include <sys/types.h>
 #include <iostream>
 #include <cstdlib>
-#include <stdio.h>
+#include <cstdio>
 
 using namespace std;
 
diff --git a/src/verilog.y b/src/verilog.y
index a32fcfce2..dd3a64b37 100644
--- a/src/verilog.y
+++ b/src/verilog.y
@@ -20,7 +20,7 @@
 //*************************************************************************
 
 %{
-#include <stdio.h>
+#include <cstdio>
 #include <cstdlib>
 #include <cstdarg>
 #include <cstring>
diff --git a/test_regress/t/t_leak.cpp b/test_regress/t/t_leak.cpp
index 067e831bb..a9f5f5efa 100644
--- a/test_regress/t/t_leak.cpp
+++ b/test_regress/t/t_leak.cpp
@@ -4,8 +4,8 @@
 // redistribute it and/or modify it under the terms of either the GNU
 // General Public License or the Perl Artistic License.
 
-#include <stdlib.h>
-#include <stdio.h>
+#include <cstdlib>
+#include <cstdio>
 #include <verilated.h>
 #include "Vt_leak.h"
 
diff --git a/test_regress/t/t_mem_slot.cpp b/test_regress/t/t_mem_slot.cpp
index dc221b17c..5394c9b4a 100644
--- a/test_regress/t/t_mem_slot.cpp
+++ b/test_regress/t/t_mem_slot.cpp
@@ -1,4 +1,4 @@
-#include <stdlib.h>
+#include <cstdlib>
 #include <verilated.h>
 #include "Vt_mem_slot.h"
 
diff --git a/test_sp/sc_main.cpp b/test_sp/sc_main.cpp
index f44557f96..1ecfdb578 100644
--- a/test_sp/sc_main.cpp
+++ b/test_sp/sc_main.cpp
@@ -6,7 +6,7 @@
 // General Public License or the Perl Artistic License.
 //====================================================================
 
-#include <stdio.h>
+#include <cstdio>
 #include <iostream>
 #include <sys/times.h>
 #include <sys/stat.h>