diff --git a/include/verilated.cpp b/include/verilated.cpp
index bb17990e0..cd0ee1122 100644
--- a/include/verilated.cpp
+++ b/include/verilated.cpp
@@ -1507,149 +1507,151 @@ void VL_FCLOSE_I(IData fdi) VL_MT_SAFE {
     Verilated::threadContextp()->impp()->fdClose(fdi);
 }
 
-void VL_SFORMAT_X(int obits, CData& destr, const std::string& format, ...) VL_MT_SAFE {
+void VL_SFORMAT_NX(int obits, CData& destr, const std::string& format, int argc, ...) VL_MT_SAFE {
     static thread_local std::string t_output;  // static only for speed
     t_output = "";
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     _vl_vsformat(t_output, format, ap);
     va_end(ap);
 
     _vl_string_to_vint(obits, &destr, t_output.length(), t_output.c_str());
 }
 
-void VL_SFORMAT_X(int obits, SData& destr, const std::string& format, ...) VL_MT_SAFE {
+void VL_SFORMAT_NX(int obits, SData& destr, const std::string& format, int argc, ...) VL_MT_SAFE {
     static thread_local std::string t_output;  // static only for speed
     t_output = "";
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     _vl_vsformat(t_output, format, ap);
     va_end(ap);
 
     _vl_string_to_vint(obits, &destr, t_output.length(), t_output.c_str());
 }
 
-void VL_SFORMAT_X(int obits, IData& destr, const std::string& format, ...) VL_MT_SAFE {
+void VL_SFORMAT_NX(int obits, IData& destr, const std::string& format, int argc, ...) VL_MT_SAFE {
     static thread_local std::string t_output;  // static only for speed
     t_output = "";
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     _vl_vsformat(t_output, format, ap);
     va_end(ap);
 
     _vl_string_to_vint(obits, &destr, t_output.length(), t_output.c_str());
 }
 
-void VL_SFORMAT_X(int obits, QData& destr, const std::string& format, ...) VL_MT_SAFE {
+void VL_SFORMAT_NX(int obits, QData& destr, const std::string& format, int argc, ...) VL_MT_SAFE {
     static thread_local std::string t_output;  // static only for speed
     t_output = "";
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     _vl_vsformat(t_output, format, ap);
     va_end(ap);
 
     _vl_string_to_vint(obits, &destr, t_output.length(), t_output.c_str());
 }
 
-void VL_SFORMAT_X(int obits, void* destp, const std::string& format, ...) VL_MT_SAFE {
+void VL_SFORMAT_NX(int obits, void* destp, const std::string& format, int argc, ...) VL_MT_SAFE {
     static thread_local std::string t_output;  // static only for speed
     t_output = "";
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     _vl_vsformat(t_output, format, ap);
     va_end(ap);
 
     _vl_string_to_vint(obits, destp, t_output.length(), t_output.c_str());
 }
 
-void VL_SFORMAT_X(int obits_ignored, std::string& output, const std::string& format,
-                  ...) VL_MT_SAFE {
-    if (obits_ignored) {}
+void VL_SFORMAT_NX(int obits_ignored, std::string& output, const std::string& format, int argc,
+                   ...) VL_MT_SAFE {
+    (void)obits_ignored;  // So VL_SFORMAT_NNX function signatures all match
     std::string temp_output;
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     _vl_vsformat(temp_output, format, ap);
     va_end(ap);
     output = temp_output;
 }
 
-std::string VL_SFORMATF_NX(const std::string& format, ...) VL_MT_SAFE {
+std::string VL_SFORMATF_N_NX(const std::string& format, int argc, ...) VL_MT_SAFE {
     static thread_local std::string t_output;  // static only for speed
     t_output = "";
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     _vl_vsformat(t_output, format, ap);
     va_end(ap);
 
     return t_output;
 }
 
-void VL_WRITEF(const std::string& format, ...) VL_MT_SAFE {
+void VL_WRITEF_NX(const std::string& format, int argc, ...) VL_MT_SAFE {
     static thread_local std::string t_output;  // static only for speed
     t_output = "";
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     _vl_vsformat(t_output, format, ap);
     va_end(ap);
 
     VL_PRINTF_MT("%s", t_output.c_str());
 }
 
-void VL_FWRITEF(IData fpi, const std::string& format, ...) VL_MT_SAFE {
+void VL_FWRITEF_NX(IData fpi, const std::string& format, int argc, ...) VL_MT_SAFE {
     // While threadsafe, each thread can only access different file handles
     static thread_local std::string t_output;  // static only for speed
     t_output = "";
 
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     _vl_vsformat(t_output, format, ap);
     va_end(ap);
 
     Verilated::threadContextp()->impp()->fdWrite(fpi, t_output);
 }
 
-IData VL_FSCANF_IX(IData fpi, const std::string& format, ...) VL_MT_SAFE {
+IData VL_FSCANF_INX(IData fpi, const std::string& format, int argc, ...) VL_MT_SAFE {
     // While threadsafe, each thread can only access different file handles
     FILE* const fp = VL_CVT_I_FP(fpi);
     if (VL_UNLIKELY(!fp)) return ~0U;  // -1
 
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     const IData got = _vl_vsscanf(fp, 0, nullptr, "", format, ap);
     va_end(ap);
     return got;
 }
 
-IData VL_SSCANF_IIX(int lbits, IData ld, const std::string& format, ...) VL_MT_SAFE {
+IData VL_SSCANF_IINX(int lbits, IData ld, const std::string& format, int argc, ...) VL_MT_SAFE {
     VlWide<VL_WQ_WORDS_E> fnw;
     VL_SET_WI(fnw, ld);
 
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     const IData got = _vl_vsscanf(nullptr, lbits, fnw, "", format, ap);
     va_end(ap);
     return got;
 }
-IData VL_SSCANF_IQX(int lbits, QData ld, const std::string& format, ...) VL_MT_SAFE {
+IData VL_SSCANF_IQNX(int lbits, QData ld, const std::string& format, int argc, ...) VL_MT_SAFE {
     VlWide<VL_WQ_WORDS_E> fnw;
     VL_SET_WQ(fnw, ld);
 
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     const IData got = _vl_vsscanf(nullptr, lbits, fnw, "", format, ap);
     va_end(ap);
     return got;
 }
-IData VL_SSCANF_IWX(int lbits, const WDataInP lwp, const std::string& format, ...) VL_MT_SAFE {
+IData VL_SSCANF_IWNX(int lbits, const WDataInP lwp, const std::string& format, int argc,
+                     ...) VL_MT_SAFE {
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     const IData got = _vl_vsscanf(nullptr, lbits, lwp, "", format, ap);
     va_end(ap);
     return got;
 }
-IData VL_SSCANF_INX(int, const std::string& ld, const std::string& format, ...) VL_MT_SAFE {
+IData VL_SSCANF_INNX(int, const std::string& ld, const std::string& format, int argc,
+                     ...) VL_MT_SAFE {
     va_list ap;
-    va_start(ap, format);
+    va_start(ap, argc);
     const IData got = _vl_vsscanf(nullptr, ld.length() * 8, nullptr, ld, format, ap);
     va_end(ap);
     return got;
@@ -1868,13 +1870,13 @@ const char* vl_mc_scan_plusargs(const char* prefixp) VL_MT_SAFE {
 //===========================================================================
 // Heavy string functions
 
-std::string VL_TO_STRING(CData lhs) { return VL_SFORMATF_NX("'h%0x", 8, lhs); }
-std::string VL_TO_STRING(SData lhs) { return VL_SFORMATF_NX("'h%0x", 16, lhs); }
-std::string VL_TO_STRING(IData lhs) { return VL_SFORMATF_NX("'h%0x", 32, lhs); }
-std::string VL_TO_STRING(QData lhs) { return VL_SFORMATF_NX("'h%0x", 64, lhs); }
-std::string VL_TO_STRING(double lhs) { return VL_SFORMATF_NX("%d", 64, lhs); }
+std::string VL_TO_STRING(CData lhs) { return VL_SFORMATF_N_NX("'h%0x", 0, 8, lhs); }
+std::string VL_TO_STRING(SData lhs) { return VL_SFORMATF_N_NX("'h%0x", 0, 16, lhs); }
+std::string VL_TO_STRING(IData lhs) { return VL_SFORMATF_N_NX("'h%0x", 0, 32, lhs); }
+std::string VL_TO_STRING(QData lhs) { return VL_SFORMATF_N_NX("'h%0x", 0, 64, lhs); }
+std::string VL_TO_STRING(double lhs) { return VL_SFORMATF_N_NX("%d", 0, 64, lhs); }
 std::string VL_TO_STRING_W(int words, const WDataInP obj) {
-    return VL_SFORMATF_NX("'h%0x", words * VL_EDATASIZE, obj);
+    return VL_SFORMATF_N_NX("'h%0x", 0, words * VL_EDATASIZE, obj);
 }
 
 std::string VL_TOLOWER_NN(const std::string& ld) VL_PURE {
diff --git a/include/verilated_funcs.h b/include/verilated_funcs.h
index 6b0413a39..c997c7d65 100644
--- a/include/verilated_funcs.h
+++ b/include/verilated_funcs.h
@@ -125,20 +125,27 @@ extern void VL_FCLOSE_I(IData fdi) VL_MT_SAFE;
 extern IData VL_FREAD_I(int width, int array_lsb, int array_size, void* memp, IData fpi,
                         IData start, IData count) VL_MT_SAFE;
 
-extern void VL_WRITEF(const std::string& format, ...) VL_MT_SAFE;
-extern void VL_FWRITEF(IData fpi, const std::string& format, ...) VL_MT_SAFE;
+extern void VL_WRITEF_NX(const std::string& format, int argc, ...) VL_MT_SAFE;
+extern void VL_FWRITEF_NX(IData fpi, const std::string& format, int argc, ...) VL_MT_SAFE;
 
-extern IData VL_FSCANF_IX(IData fpi, const std::string& format, ...) VL_MT_SAFE;
-extern IData VL_SSCANF_IIX(int lbits, IData ld, const std::string& format, ...) VL_MT_SAFE;
-extern IData VL_SSCANF_IQX(int lbits, QData ld, const std::string& format, ...) VL_MT_SAFE;
-extern IData VL_SSCANF_IWX(int lbits, WDataInP const lwp, const std::string& format,
-                           ...) VL_MT_SAFE;
+extern IData VL_FSCANF_INX(IData fpi, const std::string& format, int argc, ...) VL_MT_SAFE;
+extern IData VL_SSCANF_IINX(int lbits, IData ld, const std::string& format, int argc,
+                            ...) VL_MT_SAFE;
+extern IData VL_SSCANF_IQNX(int lbits, QData ld, const std::string& format, int argc,
+                            ...) VL_MT_SAFE;
+extern IData VL_SSCANF_IWNX(int lbits, WDataInP const lwp, const std::string& format, int argc,
+                            ...) VL_MT_SAFE;
 
-extern void VL_SFORMAT_X(int obits, CData& destr, const std::string& format, ...) VL_MT_SAFE;
-extern void VL_SFORMAT_X(int obits, SData& destr, const std::string& format, ...) VL_MT_SAFE;
-extern void VL_SFORMAT_X(int obits, IData& destr, const std::string& format, ...) VL_MT_SAFE;
-extern void VL_SFORMAT_X(int obits, QData& destr, const std::string& format, ...) VL_MT_SAFE;
-extern void VL_SFORMAT_X(int obits, void* destp, const std::string& format, ...) VL_MT_SAFE;
+extern void VL_SFORMAT_NX(int obits, CData& destr, const std::string& format, int argc,
+                          ...) VL_MT_SAFE;
+extern void VL_SFORMAT_NX(int obits, SData& destr, const std::string& format, int argc,
+                          ...) VL_MT_SAFE;
+extern void VL_SFORMAT_NX(int obits, IData& destr, const std::string& format, int argc,
+                          ...) VL_MT_SAFE;
+extern void VL_SFORMAT_NX(int obits, QData& destr, const std::string& format, int argc,
+                          ...) VL_MT_SAFE;
+extern void VL_SFORMAT_NX(int obits, void* destp, const std::string& format, int argc,
+                          ...) VL_MT_SAFE;
 
 extern void VL_STACKTRACE() VL_MT_SAFE;
 extern std::string VL_STACKTRACE_N() VL_MT_SAFE;
@@ -2291,11 +2298,11 @@ extern void VL_READMEM_N(bool hex, int bits, QData depth, int array_lsb,
 extern void VL_WRITEMEM_N(bool hex, int bits, QData depth, int array_lsb,
                           const std::string& filename, const void* memp, QData start,
                           QData end) VL_MT_SAFE;
-extern IData VL_SSCANF_INX(int lbits, const std::string& ld, const std::string& format,
-                           ...) VL_MT_SAFE;
-extern void VL_SFORMAT_X(int obits_ignored, std::string& output, const std::string& format,
-                         ...) VL_MT_SAFE;
-extern std::string VL_SFORMATF_NX(const std::string& format, ...) VL_MT_SAFE;
+extern IData VL_SSCANF_INNX(int lbits, const std::string& ld, const std::string& format, int argc,
+                            ...) VL_MT_SAFE;
+extern void VL_SFORMAT_NX(int obits_ignored, std::string& output, const std::string& format,
+                          int argc, ...) VL_MT_SAFE;
+extern std::string VL_SFORMATF_N_NX(const std::string& format, int argc, ...) VL_MT_SAFE;
 extern void VL_TIMEFORMAT_IINI(int units, int precision, const std::string& suffix, int width,
                                VerilatedContext* contextp) VL_MT_SAFE;
 extern IData VL_VALUEPLUSARGS_INW(int rbits, const std::string& ld, WDataOutP rwp) VL_MT_SAFE;
diff --git a/src/V3EmitCFunc.cpp b/src/V3EmitCFunc.cpp
index e7cae00a3..943b84d95 100644
--- a/src/V3EmitCFunc.cpp
+++ b/src/V3EmitCFunc.cpp
@@ -171,7 +171,7 @@ void EmitCFunc::displayEmit(AstNode* nodep, bool isScan) {
         bool isStmt = false;
         if (const AstFScanF* const dispp = VN_CAST(nodep, FScanF)) {
             isStmt = false;
-            putns(nodep, "VL_FSCANF_IX(");
+            putns(nodep, "VL_FSCANF_INX(");
             iterateConst(dispp->filep());
             puts(",");
         } else if (const AstSScanF* const dispp = VN_CAST(nodep, SScanF)) {
@@ -179,7 +179,7 @@ void EmitCFunc::displayEmit(AstNode* nodep, bool isScan) {
             checkMaxWords(dispp->fromp());
             putns(nodep, "VL_SSCANF_I");
             emitIQW(dispp->fromp());
-            puts("X(");
+            puts("NX(");
             puts(cvtToStr(dispp->fromp()->widthMin()));
             puts(",");
             iterateConst(dispp->fromp());
@@ -187,26 +187,27 @@ void EmitCFunc::displayEmit(AstNode* nodep, bool isScan) {
         } else if (const AstDisplay* const dispp = VN_CAST(nodep, Display)) {
             isStmt = true;
             if (dispp->filep()) {
-                putns(nodep, "VL_FWRITEF(");
+                putns(nodep, "VL_FWRITEF_NX(");
                 iterateConst(dispp->filep());
                 puts(",");
             } else {
-                putns(nodep, "VL_WRITEF(");
+                putns(nodep, "VL_WRITEF_NX(");
             }
         } else if (const AstSFormat* const dispp = VN_CAST(nodep, SFormat)) {
             isStmt = true;
-            puts("VL_SFORMAT_X(");
+            puts("VL_SFORMAT_NX(");
             puts(cvtToStr(dispp->lhsp()->widthMin()));
             putbs(",");
             iterateConst(dispp->lhsp());
             putbs(",");
         } else if (VN_IS(nodep, SFormatF)) {
             isStmt = false;
-            putns(nodep, "VL_SFORMATF_NX(");
+            putns(nodep, "VL_SFORMATF_N_NX(");
         } else {
             nodep->v3fatalSrc("Unknown displayEmit node type");
         }
         ofp()->putsQuoted(m_emitDispState.m_format);
+        ofp()->puts(",0");  // MSVC++ requires va_args to not be off reference
         // Arguments
         for (unsigned i = 0; i < m_emitDispState.m_argsp.size(); i++) {
             const char fmt = m_emitDispState.m_argsChar[i];