diff --git a/src/V3Coverage.cpp b/src/V3Coverage.cpp
index 23e3e3700..8553d9542 100644
--- a/src/V3Coverage.cpp
+++ b/src/V3Coverage.cpp
@@ -87,7 +87,7 @@ private:
 	if (!nodep->isToggleCoverable())
 	    return "Not relevant signal type";
 	if (!v3Global.opt.coverageUnderscore()) {
-	    if (prettyName.c_str()[0] == '_')
+	    if (prettyName[0] == '_')
 	        return "Leading underscore";
 	    if (prettyName.find("._") != string::npos)
 	        return "Inlined leading underscore";
diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index 3f07d5fb5..68fd3a2cb 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -563,9 +563,9 @@ bool V3Options::onoff(const char* sw, const char* arg, bool& flag) {
     return false;
 }
 
-bool V3Options::suffixed(const char* sw, const char* arg) {
-    if (strlen(arg) > strlen(sw)) return false;
-    return (0==strcmp(sw+strlen(sw)-strlen(arg), arg));
+bool V3Options::suffixed(const string& sw, const char* arg) {
+    if (strlen(arg) > sw.length()) return false;
+    return (0==strcmp(sw.c_str()+sw.length()-strlen(arg), arg));
 }
 
 void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc, char** argv) {
@@ -962,16 +962,16 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc, char
 	else {
 	    // Filename
 	    string filename = parseFileArg(optdir,argv[i]);
-	    if (suffixed(filename.c_str(), ".cpp")
-		|| suffixed(filename.c_str(), ".cxx")
-		|| suffixed(filename.c_str(), ".cc")
-		|| suffixed(filename.c_str(), ".c")
-		|| suffixed(filename.c_str(), ".sp")) {
+	    if (suffixed(filename, ".cpp")
+		|| suffixed(filename, ".cxx")
+		|| suffixed(filename, ".cc")
+		|| suffixed(filename, ".c")
+		|| suffixed(filename, ".sp")) {
 		V3Options::addCppFile(filename);
 	    }
-	    else if (suffixed(filename.c_str(), ".a")
-		     || suffixed(filename.c_str(), ".o")
-		     || suffixed(filename.c_str(), ".so")) {
+	    else if (suffixed(filename, ".a")
+		     || suffixed(filename, ".o")
+		     || suffixed(filename, ".so")) {
 		V3Options::addLdLibs(filename);
 	    }
 	    else {
diff --git a/src/V3Options.h b/src/V3Options.h
index 53749713c..1f6435446 100644
--- a/src/V3Options.h
+++ b/src/V3Options.h
@@ -168,7 +168,7 @@ class V3Options {
     void showVersion(bool verbose);
     void coverage(bool flag) { m_coverageLine = m_coverageToggle = m_coverageUser = flag; }
     bool onoff(const char* sw, const char* arg, bool& flag);
-    bool suffixed(const char* sw, const char* arg);
+    bool suffixed(const string& sw, const char* arg);
     string parseFileArg(const string& optdir, const string& relfilename);
     bool parseLangExt(const char* swp, const char* langswp, const V3LangCode& lc);
     string filePathCheckOneDir(const string& modname, const string& dirname);