diff --git a/mozilla/dbm/include/mcom_db.h b/mozilla/dbm/include/mcom_db.h
index ea812df22c5..456d5e53860 100644
--- a/mozilla/dbm/include/mcom_db.h
+++ b/mozilla/dbm/include/mcom_db.h
@@ -36,7 +36,9 @@
 #ifndef _DB_H_
 #define	_DB_H_
 
+#ifndef HAVE_SYS_CDEFS_H
 #include "cdefs.h"
+#endif
 #include "prtypes.h"
 
 #ifdef __sgi
diff --git a/mozilla/include/mcom_db.h b/mozilla/include/mcom_db.h
index 3b10b4e876d..7bcb4c3974d 100644
--- a/mozilla/include/mcom_db.h
+++ b/mozilla/include/mcom_db.h
@@ -203,7 +203,9 @@ XP_END_PROTOS
 #include <errno.h>
 #endif
 
+#ifndef HAVE_SYS_CDEFS_H
 #include "cdefs.h"
+#endif
 
 #ifndef _WINDOWS  /* included above to prevent spurious warnings chouck 12-Sep-95 */
 #include <limits.h>