diff --git a/include/verilated_threads.cpp b/include/verilated_threads.cpp
index 1c5fda43b..5cdc12b5e 100644
--- a/include/verilated_threads.cpp
+++ b/include/verilated_threads.cpp
@@ -173,12 +173,12 @@ void VlThreadPool::profileDump(const char* filenamep, vluint64_t ticksElapsed) {
             VlMTaskVertex::yields());
 
     vluint32_t thread_id = 0;
-    for (ProfileSet::iterator pit = m_allProfiles.begin();
+    for (ProfileSet::const_iterator pit = m_allProfiles.begin();
          pit != m_allProfiles.end(); ++pit) {
         ++thread_id;
 
         bool printing = false;  // False while in warmup phase
-        for (ProfileTrace::iterator eit = (*pit)->begin();
+        for (ProfileTrace::const_iterator eit = (*pit)->begin();
              eit != (*pit)->end(); ++eit) {
             switch (eit->m_type) {
             case VlProfileRec::TYPE_BARRIER:
diff --git a/src/V3Graph.cpp b/src/V3Graph.cpp
index 5233e4b6d..a15a6d2be 100644
--- a/src/V3Graph.cpp
+++ b/src/V3Graph.cpp
@@ -350,7 +350,7 @@ void V3Graph::dumpDotFile(const string& filename, bool colorAsSubgraph) const {
     // Print vertices
     int n = 0;
     string subgr;
-    for (SubgraphMmap::iterator it = subgraphs.begin(); it!=subgraphs.end(); ++it) {
+    for (SubgraphMmap::const_iterator it = subgraphs.begin(); it != subgraphs.end(); ++it) {
         string vertexSubgraph = it->first;
         V3GraphVertex* vertexp = it->second;
         numMap[vertexp] = n;
diff --git a/src/V3LanguageWords.h b/src/V3LanguageWords.h
index 2319ecfe8..aab0466cc 100644
--- a/src/V3LanguageWords.h
+++ b/src/V3LanguageWords.h
@@ -46,7 +46,7 @@ class V3LanguageWords {
     static const_iterator begin() { return s().s_kwdMap.begin(); }
     static const_iterator end() { return s().s_kwdMap.end(); }
     static string isKeyword(const string& kwd) {
-        KeywordMap::iterator it = s().s_kwdMap.find(kwd);
+        KeywordMap::const_iterator it = s().s_kwdMap.find(kwd);
         if (it == s().s_kwdMap.end()) return "";
         return it->second;
     }
diff --git a/src/V3LinkLevel.cpp b/src/V3LinkLevel.cpp
index abdfa423a..2d91daf5e 100644
--- a/src/V3LinkLevel.cpp
+++ b/src/V3LinkLevel.cpp
@@ -55,11 +55,9 @@ void V3LinkLevel::modSortByLevel() {
 
     ModVec mods;  // Modules
     ModVec tops;  // Top level modules
-    for (AstNodeModule* nodep = v3Global.rootp()->modulesp();
-         nodep; nodep=VN_CAST(nodep->nextp(), NodeModule)) {
-        if (nodep->level()<=2) {
-            tops.push_back(nodep);
-        }
+    for (AstNodeModule* nodep = v3Global.rootp()->modulesp(); nodep;
+         nodep = VN_CAST(nodep->nextp(), NodeModule)) {
+        if (nodep->level() <= 2) tops.push_back(nodep);
         mods.push_back(nodep);
     }
     if (tops.size() >= 2) {
@@ -69,7 +67,7 @@ void V3LinkLevel::modSortByLevel() {
                          <<secp->warnMore()
                          <<"... Suggest see manual; fix the duplicates, or use --top-module to select top."
                          <<V3Error::warnContextNone());
-            for (ModVec::iterator it = tops.begin(); it != tops.end(); ++it) {
+            for (ModVec::const_iterator it = tops.begin(); it != tops.end(); ++it) {
                 AstNode* alsop = *it;
                 std::cout<<secp->warnMore()<<"... Top module "<<alsop->prettyNameQ()<<endl
                          <<alsop->warnContextSecondary();
diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index 71500599f..48b40f45d 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -247,7 +247,7 @@ void V3Options::addArg(const string& arg) {
 
 string V3Options::allArgsString() {
     string out;
-    for (std::list<string>::iterator it=m_impp->m_allArgs.begin();
+    for (std::list<string>::const_iterator it = m_impp->m_allArgs.begin();
          it != m_impp->m_allArgs.end(); ++it) {
         if (out != "") out += " ";
         out += *it;
diff --git a/src/V3Partition.h b/src/V3Partition.h
index dfa737b0b..21fb3560c 100644
--- a/src/V3Partition.h
+++ b/src/V3Partition.h
@@ -88,10 +88,8 @@ public:
     PartPtrIdMap() : m_nextId(0) {}
     // METHODS
     vluint64_t findId(const void* ptrp) const {
-        PtrMap::iterator it = m_id.find(ptrp);
-        if (it != m_id.end()) {
-            return it->second;
-        }
+        PtrMap::const_iterator it = m_id.find(ptrp);
+        if (it != m_id.end()) return it->second;
         m_id[ptrp] = m_nextId;
         return m_nextId++;
     }
diff --git a/src/V3StatsReport.cpp b/src/V3StatsReport.cpp
index a40fd5727..ec2152433 100644
--- a/src/V3StatsReport.cpp
+++ b/src/V3StatsReport.cpp
@@ -140,12 +140,12 @@ class StatsReport {
 
         // Header
         os<<"  Stat     "<<std::left<<std::setw(maxWidth-5-2)<<"";
-        for (Stages::iterator it = stages.begin(); it!=stages.end(); ++it) {
+        for (Stages::const_iterator it = stages.begin(); it != stages.end(); ++it) {
             os<<"  "<<std::left<<std::setw(9)<<*it;
         }
         os<<endl;
         os<<"  -------- "<<std::left<<std::setw(maxWidth-5-2)<<"";
-        for (Stages::iterator it = stages.begin(); it!=stages.end(); ++it) {
+        for (Stages::const_iterator it = stages.begin(); it != stages.end(); ++it) {
             os<<"  "<<std::left<<std::setw(9)<<"-------";
         }
         //os<<endl;
@@ -154,7 +154,7 @@ class StatsReport {
         string lastName = "__NONE__";
         string lastCommaName = "__NONE__";
         unsigned col = 0;
-        for (ByName::iterator it = byName.begin(); it!=byName.end(); ++it) {
+        for (ByName::const_iterator it = byName.begin(); it != byName.end(); ++it) {
             const V3Statistic* repp = it->second;
             if (lastName != repp->name()) {
                 lastName = repp->name();
diff --git a/src/V3TSP.cpp b/src/V3TSP.cpp
index 8a9d2751b..f829dcc3c 100644
--- a/src/V3TSP.cpp
+++ b/src/V3TSP.cpp
@@ -689,7 +689,7 @@ void V3TSP::selfTestString() {
     expect.push_back("3");
 
     if (VL_UNCOVERABLE(expect != result)) {
-        for (std::vector<string>::iterator it = result.begin(); it != result.end(); ++it) {
+        for (std::vector<string>::const_iterator it = result.begin(); it != result.end(); ++it) {
             cout<<*it<<" ";
         }
         cout<<endl;
diff --git a/src/VlcMain.cpp b/src/VlcMain.cpp
index 99e018446..788f136d0 100644
--- a/src/VlcMain.cpp
+++ b/src/VlcMain.cpp
@@ -157,7 +157,7 @@ int main(int argc, char** argv, char** env) {
 
     {
         const VlStringSet& readFiles = top.opt.readFiles();
-        for (VlStringSet::iterator it = readFiles.begin(); it != readFiles.end(); ++it) {
+        for (VlStringSet::const_iterator it = readFiles.begin(); it != readFiles.end(); ++it) {
             string filename = *it;
             top.readCoverage(filename);
         }
@@ -183,7 +183,7 @@ int main(int argc, char** argv, char** env) {
         V3Error::abortIfWarnings();
         if (top.opt.unlink()) {
             const VlStringSet& readFiles = top.opt.readFiles();
-            for (VlStringSet::iterator it = readFiles.begin(); it != readFiles.end(); ++it) {
+            for (VlStringSet::const_iterator it = readFiles.begin(); it != readFiles.end(); ++it) {
                 string filename = *it;
                 unlink(filename.c_str());
             }
diff --git a/src/VlcPoint.h b/src/VlcPoint.h
index d333c7fcb..aaa3f6b78 100644
--- a/src/VlcPoint.h
+++ b/src/VlcPoint.h
@@ -123,7 +123,7 @@ public:
     void dump() {
         UINFO(2,"dumpPoints...\n");
         VlcPoint::dumpHeader();
-        for (VlcPoints::ByName::iterator it=begin(); it!=end(); ++it) {
+        for (VlcPoints::ByName::const_iterator it = begin(); it != end(); ++it) {
             const VlcPoint& point = pointNumber(it->second);
             point.dump();
         }
@@ -133,7 +133,7 @@ public:
     }
     vluint64_t findAddPoint(const string& name, vluint64_t count) {
         vluint64_t pointnum;
-        NameMap::iterator iter = m_nameMap.find(name);
+        NameMap::const_iterator iter = m_nameMap.find(name);
         if (iter != m_nameMap.end()) {
             pointnum = iter->second;
             m_points[pointnum].countInc(count);
diff --git a/src/VlcTest.h b/src/VlcTest.h
index 3411f97e6..89ab1ead5 100644
--- a/src/VlcTest.h
+++ b/src/VlcTest.h
@@ -118,7 +118,7 @@ public:
     void dump(bool bucketsToo) {
         UINFO(2,"dumpTests...\n");
         VlcTest::dumpHeader();
-        for (VlcTests::ByName::iterator it=begin(); it!=end(); ++it) {
+        for (VlcTests::ByName::const_iterator it = begin(); it != end(); ++it) {
             (*it)->dump(bucketsToo);
         }
     }
diff --git a/src/VlcTop.cpp b/src/VlcTop.cpp
index d18c9a56d..a353bdbbb 100644
--- a/src/VlcTop.cpp
+++ b/src/VlcTop.cpp
@@ -75,7 +75,7 @@ void VlcTop::writeCoverage(const string& filename) {
     }
 
     os << "# SystemC::Coverage-3" << endl;
-    for (VlcPoints::ByName::iterator it=m_points.begin(); it!=m_points.end(); ++it) {
+    for (VlcPoints::ByName::const_iterator it = m_points.begin(); it != m_points.end(); ++it) {
         const VlcPoint& point = m_points.pointNumber(it->second);
         os <<"C '"<<point.name()<<"' " << point.count()<<endl;
     }
@@ -98,7 +98,7 @@ void VlcTop::rank() {
 
     // Sort by computrons, so fast tests get selected first
     std::vector<VlcTest*> bytime;
-    for (VlcTests::ByName::iterator it=m_tests.begin(); it!=m_tests.end(); ++it) {
+    for (VlcTests::ByName::const_iterator it = m_tests.begin(); it != m_tests.end(); ++it) {
         VlcTest* testp = *it;
         if (testp->bucketsCovered()) {  // else no points, so can't help us
             bytime.push_back(*it);
@@ -107,7 +107,7 @@ void VlcTop::rank() {
     sort(bytime.begin(), bytime.end(), CmpComputrons());  // Sort the vector
 
     VlcBuckets remaining;
-    for (VlcPoints::ByName::iterator it=m_points.begin(); it!=m_points.end(); ++it) {
+    for (VlcPoints::ByName::const_iterator it = m_points.begin(); it != m_points.end(); ++it) {
         VlcPoint* pointp = &points().pointNumber(it->second);
         // If any tests hit this point, then we'll need to cover it.
         if (pointp->testsCovering()) { remaining.addData(pointp->pointNum(), 1); }
@@ -145,7 +145,7 @@ void VlcTop::rank() {
 
 void VlcTop::annotateCalc() {
     // Calculate per-line information into filedata structure
-    for (VlcPoints::ByName::iterator it=m_points.begin(); it!=m_points.end(); ++it) {
+    for (VlcPoints::ByName::const_iterator it = m_points.begin(); it != m_points.end(); ++it) {
         const VlcPoint& point = m_points.pointNumber(it->second);
         string filename = point.filename();
         int lineno = point.lineno();
@@ -171,9 +171,10 @@ void VlcTop::annotateCalcNeeded() {
         //UINFO(1,"Source "<<source.name()<<endl);
         if (opt.annotateAll()) source.needed(true);
         VlcSource::LinenoMap& lines = source.lines();
-        for (VlcSource::LinenoMap::iterator lit=lines.begin(); lit!=lines.end(); ++lit) {
+        for (VlcSource::LinenoMap::iterator lit = lines.begin(); lit != lines.end(); ++lit) {
             VlcSource::ColumnMap& cmap = lit->second;
-            for (VlcSource::ColumnMap::iterator cit=cmap.begin(); cit!=cmap.end(); ++cit) {
+            for (VlcSource::ColumnMap::iterator cit = cmap.begin(); cit != cmap.end();
+                 ++cit) {
                 VlcSourceCount& col = cit->second;
                 //UINFO(0,"Source "<<source.name()<<":"<<col.lineno()<<":"<<col.column()<<endl);
                 ++totCases;
@@ -227,7 +228,8 @@ void VlcTop::annotateOutputFiles(const string& dirname) {
             VlcSource::LinenoMap::iterator lit=lines.find(lineno);
             if (lit != lines.end()) {
                 VlcSource::ColumnMap& cmap = lit->second;
-                for (VlcSource::ColumnMap::iterator cit=cmap.begin(); cit!=cmap.end(); ++cit) {
+                for (VlcSource::ColumnMap::iterator cit = cmap.begin(); cit != cmap.end();
+                     ++cit) {
                     VlcSourceCount& col = cit->second;
                     //UINFO(0,"Source "<<source.name()<<":"<<col.lineno()<<":"<<col.column()<<endl);
                     os<<(col.ok()?" ":"%")