diff --git a/src/V3EmitC.cpp b/src/V3EmitC.cpp
index 54fb59e2a..c6ebe76fe 100644
--- a/src/V3EmitC.cpp
+++ b/src/V3EmitC.cpp
@@ -1073,8 +1073,6 @@ class EmitCImp : EmitCStmts {
             }
             ofp->puts("// See "+v3Global.opt.prefix()+".h for the primary calling header\n");
         }
-        ofp->puts("\n");
-
         return ofp;
     }
 
@@ -2536,8 +2534,7 @@ void EmitCImp::emitMTaskState() {
 
 void EmitCImp::emitInt(AstNodeModule* modp) {
     // Always have this first; gcc has short circuiting if #ifdef is first in a file
-    puts("#ifndef _"+modClassName(modp)+"_H_\n");
-    puts("#define _"+modClassName(modp)+"_H_\n");
+    ofp()->putsGuard();
     puts("\n");
 
     ofp()->putsIntTopInclude();
@@ -2757,12 +2754,13 @@ void EmitCImp::emitInt(AstNodeModule* modp) {
     }
 
     // finish up h-file
-    puts("#endif  // guard\n");
+    ofp()->putsEndGuard();
 }
 
 //----------------------------------------------------------------------
 
 void EmitCImp::emitImp(AstNodeModule* modp) {
+    puts("\n");
     puts("#include \""+modClassName(modp)+".h\"\n");
     puts("#include \""+symClassName()+".h\"\n");
 
@@ -2770,8 +2768,8 @@ void EmitCImp::emitImp(AstNodeModule* modp) {
         puts("\n");
         puts("#include \"verilated_dpi.h\"\n");
     }
-    puts("\n");
 
+    puts("\n");
     emitTextSection(AstType::atScImpHdr);
 
     if (m_slow && splitFilenum()==0) {
diff --git a/src/V3EmitCInlines.cpp b/src/V3EmitCInlines.cpp
index 28946e809..344d29e13 100644
--- a/src/V3EmitCInlines.cpp
+++ b/src/V3EmitCInlines.cpp
@@ -101,8 +101,7 @@ void EmitCInlines::emitInt() {
     m_ofp = &hf;
 
     ofp()->putsHeader();
-    puts("#ifndef _"+topClassName()+"__Inlines_H_\n");
-    puts("#define _"+topClassName()+"__Inlines_H_\n");
+    ofp()->putsGuard();
     puts("\n");
 
     puts("#include \"verilated.h\"\n");
@@ -112,7 +111,7 @@ void EmitCInlines::emitInt() {
     // Placeholder - v3Global.needHInlines(true) currently not used
 
     puts("//======================\n\n");
-    puts("#endif  // guard\n");
+    ofp()->putsEndGuard();
 }
 
 //######################################################################
diff --git a/src/V3EmitCSyms.cpp b/src/V3EmitCSyms.cpp
index dfbc62b73..5b55a02e7 100644
--- a/src/V3EmitCSyms.cpp
+++ b/src/V3EmitCSyms.cpp
@@ -372,12 +372,10 @@ void EmitCSyms::emitSymHdr() {
     puts("//\n");
     puts("// Internal details; most calling programs do not need this header,\n");
     puts("// unless using verilator public meta comments.\n");
-    puts("\n");
 
-    puts("#ifndef _"+symClassName()+"_H_\n");
-    puts("#define _"+symClassName()+"_H_\n");
-    puts("\n");
+    ofp()->putsGuard();
 
+    puts("\n");
     ofp()->putsIntTopInclude();
     if (v3Global.needHeavy()) {
         puts("#include \"verilated_heavy.h\"\n");
@@ -474,8 +472,8 @@ void EmitCSyms::emitSymHdr() {
     }
     puts("\n");
     puts("} VL_ATTR_ALIGNED(64);\n");
-    puts("\n");
-    puts("#endif  // guard\n");
+
+    ofp()->putsEndGuard();
 }
 
 void EmitCSyms::closeSplit() {
diff --git a/src/V3File.cpp b/src/V3File.cpp
index cbf857e9b..46c81ded5 100644
--- a/src/V3File.cpp
+++ b/src/V3File.cpp
@@ -25,6 +25,7 @@
 #include "V3File.h"
 #include "V3Os.h"
 #include "V3PreShell.h"
+#include "V3String.h"
 #include "V3Ast.h"
 
 #include <cerrno>
@@ -942,6 +943,17 @@ void V3OutFile::putsForceIncs() {
     }
 }
 
+void V3OutCFile::putsGuard() {
+    UASSERT(!m_guard, "Already called putsGuard in emit file");
+    m_guard = true;
+    string var = VString::upcase(string("_") + V3Os::filenameNonDir(filename()) + "_");
+    for (string::iterator pos = var.begin(); pos != var.end(); ++pos) {
+        if (!isalnum(*pos)) *pos = '_';
+    }
+    puts("\n#ifndef " + var + "\n");
+    puts("#define " + var + "  // guard\n");
+}
+
 //######################################################################
 // VIdProtect
 
diff --git a/src/V3File.h b/src/V3File.h
index 2c0997283..3f429ed66 100644
--- a/src/V3File.h
+++ b/src/V3File.h
@@ -138,6 +138,7 @@ public:
     V3OutFormatter(const string& filename, Language lang);
     virtual ~V3OutFormatter() {}
     // ACCESSORS
+    string filename() const { return m_filename; }
     int column() const { return m_column; }
     int blockIndent() const { return m_blockIndent; }
     void blockIndent(int flag) { m_blockIndent = flag; }
@@ -186,23 +187,28 @@ private:
 };
 
 class V3OutCFile : public V3OutFile {
-    int         m_private;
+    int m_guard;  // Created header guard
+    int m_private;  // 1 = Most recently emitted private:, 2 = public:
 public:
-    explicit V3OutCFile(const string& filename) : V3OutFile(filename, V3OutFormatter::LA_C) {
+    explicit V3OutCFile(const string& filename)
+        : V3OutFile(filename, V3OutFormatter::LA_C)
+        , m_guard(false) {
         resetPrivate();
     }
     virtual ~V3OutCFile() {}
     virtual void putsHeader() { puts("// Verilated -*- C++ -*-\n"); }
-    virtual void putsIntTopInclude() {
-        putsForceIncs();
+    virtual void putsIntTopInclude() { putsForceIncs(); }
+    virtual void putsGuard();
+    virtual void putsEndGuard() {
+        if (m_guard) puts("\n#endif  // guard\n");
     }
     // Print out public/privates
     void resetPrivate() { m_private = 0; }
     void putsPrivate(bool setPrivate) {
-        if (setPrivate && m_private!=1) {
+        if (setPrivate && m_private != 1) {
             puts("private:\n");
             m_private = 1;
-        } else if (!setPrivate && m_private!=2) {
+        } else if (!setPrivate && m_private != 2) {
             puts("public:\n");
             m_private = 2;
         }
diff --git a/src/V3String.cpp b/src/V3String.cpp
index 79869dbdf..9e1a5b0d6 100644
--- a/src/V3String.cpp
+++ b/src/V3String.cpp
@@ -88,6 +88,14 @@ string VString::downcase(const string& str) {
     return out;
 }
 
+string VString::upcase(const string& str) {
+    string out = str;
+    for (string::iterator pos = out.begin(); pos != out.end(); ++pos) {
+        *pos = toupper(*pos);
+    }
+    return out;
+}
+
 string VString::quotePercent(const string& str) {
     string out;
     for (string::const_iterator pos = str.begin(); pos != str.end(); ++pos) {
diff --git a/src/V3String.h b/src/V3String.h
index d04629606..ace8428c3 100644
--- a/src/V3String.h
+++ b/src/V3String.h
@@ -65,8 +65,10 @@ public:
     static bool wildmatch(const char* s, const char* p);
     // Return {a}{dot}{b}, omitting dot if a or b are empty
     static string dot(const string& a, const string& dot, const string& b);
-    // Convert string to lowercase
+    // Convert string to lowercase (tolower)
     static string downcase(const string& str);
+    // Convert string to upper case (toupper)
+    static string upcase(const string& str);
     // Replace any %'s with %%
     static string quotePercent(const string& str);
     // Replace any unprintable with space