diff --git a/src/dmd/dtoh.d b/src/dmd/dtoh.d
index 869142211434..d40464daff36 100644
--- a/src/dmd/dtoh.d
+++ b/src/dmd/dtoh.d
@@ -22,12 +22,7 @@ import dmd.astcodegen;
 import dmd.arraytypes;
 import dmd.globals;
 import dmd.identifier;
-import dmd.json;
-import dmd.mars;
-import dmd.root.array;
-import dmd.root.file;
 import dmd.root.filename;
-import dmd.root.rmem;
 import dmd.visitor;
 import dmd.tokens;
 
@@ -193,14 +188,14 @@ private void initialize()
     }
 }
 
-void genCppHdrFiles(ref Modules ms)
+extern(C++) void genCppHdrFiles(ref Modules ms)
 {
     initialize();
 
     OutBuffer buf;
-    buf.writestring("#pragma once\n");
+    buf.printf("// Automatically generated by %s Compiler v%d\n", global.vendor.ptr, global.versionNumber());
     buf.writeByte('\n');
-    buf.printf("// Automatically generated by dmd -HC\n");
+    buf.writestring("#pragma once\n");
     buf.writeByte('\n');
     buf.writestring("#include <assert.h>\n");
     buf.writestring("#include <stddef.h>\n");
diff --git a/src/dmd/hdrgen.h b/src/dmd/hdrgen.h
index 2478a6563689..a945c77b4a7c 100644
--- a/src/dmd/hdrgen.h
+++ b/src/dmd/hdrgen.h
@@ -16,5 +16,6 @@
 class Module;
 
 void genhdrfile(Module *m);
+void genCppHdrFiles(Modules &ms);
 void moduleToBuffer(OutBuffer *buf, Module *m);
 const char *parametersTypeToChars(ParameterList pl);
diff --git a/test/compilable/dtoh_AliasDeclaration.d b/test/compilable/dtoh_AliasDeclaration.d
index 1314e2b6b1db..fd62a5f284f6 100644
--- a/test/compilable/dtoh_AliasDeclaration.d
+++ b/test/compilable/dtoh_AliasDeclaration.d
@@ -3,9 +3,9 @@ REQUIRED_ARGS: -HC -c -o-
 PERMUTE_ARGS:
 TEST_OUTPUT:
 ---
-#pragma once
+// Automatically generated by Digital Mars D Compiler v$n$
 
-// Automatically generated by dmd -HC
+#pragma once
 
 #include <assert.h>
 #include <stddef.h>
diff --git a/test/compilable/dtoh_AnonDeclaration.d b/test/compilable/dtoh_AnonDeclaration.d
index c55b07638037..468ae94d75ea 100644
--- a/test/compilable/dtoh_AnonDeclaration.d
+++ b/test/compilable/dtoh_AnonDeclaration.d
@@ -3,9 +3,9 @@ REQUIRED_ARGS: -HC -c -o-
 PERMUTE_ARGS:
 TEST_OUTPUT:
 ---
-#pragma once
+// Automatically generated by Digital Mars D Compiler v$n$
 
-// Automatically generated by dmd -HC
+#pragma once
 
 #include <assert.h>
 #include <stddef.h>
diff --git a/test/compilable/dtoh_ClassDeclaration.d b/test/compilable/dtoh_ClassDeclaration.d
index 2e2a65eb9de2..3ff8e96c57a0 100644
--- a/test/compilable/dtoh_ClassDeclaration.d
+++ b/test/compilable/dtoh_ClassDeclaration.d
@@ -3,9 +3,9 @@ REQUIRED_ARGS: -HC -c -o-
 PERMUTE_ARGS:
 TEST_OUTPUT:
 ---
-#pragma once
+// Automatically generated by Digital Mars D Compiler v$n$
 
-// Automatically generated by dmd -HC
+#pragma once
 
 #include <assert.h>
 #include <stddef.h>
diff --git a/test/compilable/dtoh_StructDeclaration.d b/test/compilable/dtoh_StructDeclaration.d
index ec31b974f003..57759929e462 100644
--- a/test/compilable/dtoh_StructDeclaration.d
+++ b/test/compilable/dtoh_StructDeclaration.d
@@ -3,9 +3,9 @@ REQUIRED_ARGS: -HC -c -o-
 PERMUTE_ARGS:
 TEST_OUTPUT:
 ---
-#pragma once
+// Automatically generated by Digital Mars D Compiler v$n$
 
-// Automatically generated by dmd -HC
+#pragma once
 
 #include <assert.h>
 #include <stddef.h>
diff --git a/test/compilable/dtoh_TemplateDeclaration.d b/test/compilable/dtoh_TemplateDeclaration.d
index 857d1a214099..522c44a16beb 100644
--- a/test/compilable/dtoh_TemplateDeclaration.d
+++ b/test/compilable/dtoh_TemplateDeclaration.d
@@ -3,9 +3,9 @@ REQUIRED_ARGS: -HC -c -o-
 PERMUTE_ARGS:
 TEST_OUTPUT:
 ---
-#pragma once
+// Automatically generated by Digital Mars D Compiler v$n$
 
-// Automatically generated by dmd -HC
+#pragma once
 
 #include <assert.h>
 #include <stddef.h>
diff --git a/test/compilable/dtoh_VarDeclaration.d b/test/compilable/dtoh_VarDeclaration.d
index 545564833d19..e34bb86e1791 100644
--- a/test/compilable/dtoh_VarDeclaration.d
+++ b/test/compilable/dtoh_VarDeclaration.d
@@ -3,9 +3,9 @@ REQUIRED_ARGS: -HC -c -o-
 PERMUTE_ARGS:
 TEST_OUTPUT:
 ---
-#pragma once
+// Automatically generated by Digital Mars D Compiler v$n$
 
-// Automatically generated by dmd -HC
+#pragma once
 
 #include <assert.h>
 #include <stddef.h>
diff --git a/test/compilable/dtoh_enum.d b/test/compilable/dtoh_enum.d
index 0e3381fce2c5..a7238e253861 100644
--- a/test/compilable/dtoh_enum.d
+++ b/test/compilable/dtoh_enum.d
@@ -3,9 +3,9 @@ REQUIRED_ARGS: -HC -c -o-
 PERMUTE_ARGS:
 TEST_OUTPUT:
 ---
-#pragma once
+// Automatically generated by Digital Mars D Compiler v$n$
 
-// Automatically generated by dmd -HC
+#pragma once
 
 #include <assert.h>
 #include <stddef.h>
diff --git a/test/compilable/dtoh_functions.d b/test/compilable/dtoh_functions.d
index 5071bd7206eb..a4760208a7c1 100644
--- a/test/compilable/dtoh_functions.d
+++ b/test/compilable/dtoh_functions.d
@@ -3,9 +3,9 @@ REQUIRED_ARGS: -HC -c -o-
 PERMUTE_ARGS:
 TEST_OUTPUT:
 ---
-#pragma once
+// Automatically generated by Digital Mars D Compiler v$n$
 
-// Automatically generated by dmd -HC
+#pragma once
 
 #include <assert.h>
 #include <stddef.h>
diff --git a/test/compilable/dtoh_unittest_block.d b/test/compilable/dtoh_unittest_block.d
index 965c66ae34ba..763ba9190f3a 100644
--- a/test/compilable/dtoh_unittest_block.d
+++ b/test/compilable/dtoh_unittest_block.d
@@ -3,9 +3,9 @@ REQUIRED_ARGS: -HC -c -o-
 PERMUTE_ARGS:
 TEST_OUTPUT:
 ---
-#pragma once
+// Automatically generated by Digital Mars D Compiler v$n$
 
-// Automatically generated by dmd -HC
+#pragma once
 
 #include <assert.h>
 #include <stddef.h>