diff --git a/xpcom/typelib/xpidl/xpidl_header.c b/xpcom/typelib/xpidl/xpidl_header.c
index 57672472b481..c576acb33e0e 100644
--- a/xpcom/typelib/xpidl/xpidl_header.c
+++ b/xpcom/typelib/xpidl/xpidl_header.c
@@ -83,12 +83,15 @@ interface(TreeState *state)
 {
     IDL_tree iface = state->tree, iter, orig;
     char *className = IDL_IDENT(IDL_INTERFACE(iface).ident).str;
-    char *classNameUpper;
+    char *classNameUpper = NULL, *cp;
+    gboolean ok = TRUE;
     const char *iid;
     const char *name_space;
     struct nsID id;
     char iid_parsed[UUID_LENGTH];
 
+#define FAIL    do {ok = FALSE; goto out;} while(0)
+
     orig = state->tree;
 
     fprintf(state->file,   "\n/* starting interface:    %s */\n",
@@ -108,7 +111,7 @@ interface(TreeState *state)
         /* Redundant, but a better error than 'cannot parse.' */
         if (strlen(iid) != 36) {
             IDL_tree_error(state->tree, "IID %s is the wrong length\n", iid);
-            return FALSE;
+            FAIL;
         }
 
         /*
@@ -117,11 +120,11 @@ interface(TreeState *state)
          */
         if (!xpidl_parse_iid(&id, iid)) {
             IDL_tree_error(state->tree, "cannot parse IID %s\n", iid);
-            return FALSE;
+            FAIL;
         }
         if (!xpidl_sprint_iid(&id, iid_parsed)) {
             IDL_tree_error(state->tree, "error formatting IID %s\n", iid);
-            return FALSE;
+            FAIL;
         }
 
         /* #define NS_ISUPPORTS_IID_STR "00000000-0000-0000-c000-000000000046" */
@@ -166,7 +169,7 @@ interface(TreeState *state)
     state->tree = IDL_INTERFACE(iface).body;
 
     if (state->tree && !xpidl_process_node(state))
-        return FALSE;
+        FAIL;
 
     fputs("};\n", state->file);
     fputc('\n', state->file);
@@ -182,10 +185,10 @@ interface(TreeState *state)
     fputs("/* Use this macro when declaring classes that implement this "
           "interface. */\n", state->file);
     fputs("#define NS_DECL_", state->file);
-    classNameUpper = className;
-    while (*classNameUpper != '\0')
-        fputc(toupper(*classNameUpper++), state->file);
-    fputs(" \\\n", state->file);
+    classNameUpper = xpidl_strdup(className);
+    for (cp = classNameUpper; *cp != '\0'; cp++)
+        *cp = toupper(*cp);
+    fprintf(state->file, "%s \\\n", classNameUpper);
     if (IDL_INTERFACE(state->tree).body == NULL) {
         write_indent(state->file);
         fputs("/* no methods! */\n", state->file);
@@ -206,12 +209,12 @@ interface(TreeState *state)
           case IDLN_ATTR_DCL:
             write_indent(state->file);
             if (!write_attr_accessor(data, state->file, TRUE, FALSE))
-                return FALSE;
+                FAIL;
             if (!IDL_ATTR_DCL(data).f_readonly) {
                 fputs("; \\\n", state->file); /* Terminate the previous one. */
                 write_indent(state->file);
                 if (!write_attr_accessor(data, state->file, FALSE, FALSE))
-                    return FALSE;
+                    FAIL;
                 /* '; \n' at end will clean up. */
             }
             break;
@@ -223,10 +226,10 @@ interface(TreeState *state)
           case IDLN_CODEFRAG:
             XPIDL_WARNING((iter, IDL_WARNING1,
                            "%%{ .. %%} code fragment within interface "
-                           "ignored when generating NS_DECL_IFOO macro; "
+                           "ignored when generating NS_DECL_%s macro; "
                            "if the code fragment contains method "
                            "declarations, the macro probably isn't "
-                           "complete."));
+                           "complete.", classNameUpper));
             continue;
 
           default:
@@ -234,7 +237,7 @@ interface(TreeState *state)
                            "unexpected node type %d! "
                            "Please file a bug against the xpidl component.",
                            IDL_NODE_TYPE(data));
-            return FALSE;
+            FAIL;
         }
 
         if (IDL_LIST(iter).next != NULL) {
@@ -251,13 +254,11 @@ interface(TreeState *state)
      * behavior from in implementation to another object.  As generated by
      * idlc.
      */
-    fputs("/* Use this macro to declare functions that forward the behavior of "
-          "this interface to another object. */\n", state->file);
-    fputs("#define NS_FORWARD_", state->file);
-    classNameUpper = className;
-    while (*classNameUpper != '\0')
-        fputc(toupper(*classNameUpper++), state->file);
-    fputs("(_to) \\\n", state->file);
+    fprintf(state->file,
+            "/* Use this macro to declare functions that forward the "
+            "behavior of this interface to another object. */\n"
+            "#define NS_FORWARD_%s(_to) \\\n",
+            classNameUpper);
     if (IDL_INTERFACE(state->tree).body == NULL) {
         write_indent(state->file);
         fputs("/* no methods! */\n", state->file);
@@ -280,18 +281,18 @@ interface(TreeState *state)
           case IDLN_ATTR_DCL:
             write_indent(state->file);
             if (!write_attr_accessor(data, state->file, TRUE, FALSE))
-                return FALSE;
+                FAIL;
             fputs(" { return _to ## ", state->file);
             if (!write_attr_accessor(data, state->file, TRUE, TRUE))
-                return FALSE;
+                FAIL;
             if (!IDL_ATTR_DCL(data).f_readonly) {
                 fputs("; } \\\n", state->file); /* Terminate the previous one. */
                 write_indent(state->file);
                 if (!write_attr_accessor(data, state->file, FALSE, FALSE))
-                    return FALSE;
+                    FAIL;
                 fputs(" { return _to ## ", state->file);
                 if (!write_attr_accessor(data, state->file, FALSE, TRUE))
-                    return FALSE;
+                    FAIL;
                 /* '; } \n' at end will clean up. */
             }
             break;
@@ -301,7 +302,7 @@ interface(TreeState *state)
               continue;
 
           default:
-            return FALSE;
+            FAIL;
         }
 
         if (IDL_LIST(iter).next != NULL) {
@@ -312,7 +313,12 @@ interface(TreeState *state)
     }
     fputc('\n', state->file);
 
-    return TRUE;
+#undef FAIL
+
+out:
+    if (classNameUpper)
+        free(classNameUpper);
+    return ok;
 }
 
 static gboolean