diff --git a/mozilla/modules/libpref/public/nsIPref.idl b/mozilla/modules/libpref/public/nsIPref.idl
index bb42a8a1544..fc5c5f5d293 100644
--- a/mozilla/modules/libpref/public/nsIPref.idl
+++ b/mozilla/modules/libpref/public/nsIPref.idl
@@ -26,7 +26,7 @@
 #include "jsapi.h"
 
 
-typedef int (*PrefChangedFunc)(const char *, void *);
+typedef int (*PR_CALLBACK PrefChangedFunc)(const char *, void *);
 typedef void (*PrefEnumerationFunc)(const char *, void *);
  
 #define NS_PREF_CID                                    \
diff --git a/mozilla/modules/libpref/src/nsPref.cpp b/mozilla/modules/libpref/src/nsPref.cpp
index 28a4e38b987..1a97e622165 100644
--- a/mozilla/modules/libpref/src/nsPref.cpp
+++ b/mozilla/modules/libpref/src/nsPref.cpp
@@ -19,6 +19,18 @@
  *
  * Contributor(s): 
  *   Pierre Phaneuf <pp@ludusdesign.com>
+ *
+ * This Original Code has been modified by IBM Corporation.
+ * Modifications made by IBM described herein are
+ * Copyright (c) International Business Machines
+ * Corporation, 2000
+ *
+ * Modifications to Mozilla code or documentation
+ * identified per MPL Section 3.3
+ *
+ * Date         Modified by     Description of modification
+ * 03/27/2000   IBM Corp.       Added PR_CALLBACK for Optlink
+ *                               use in OS2
  */
 
 #include "nsIPref.h"
@@ -890,7 +902,7 @@ typedef struct
   and entry is
   "a.b.c" or "a.b"
   then add "a.b" to the list. */
-static PR_CALLBACK PRIntn
+static PRIntn PR_CALLBACK
 pref_addChild(PLHashEntry *he, int i, void *arg)
 {
 	PrefChildIter* pcs = (PrefChildIter*) arg;