diff --git a/build/autoconf/myconfig2defs.sh b/build/autoconf/myconfig2defs.sh
index e1b502bdec8..8f54e071037 100755
--- a/build/autoconf/myconfig2defs.sh
+++ b/build/autoconf/myconfig2defs.sh
@@ -87,6 +87,9 @@ myconfig_ac_options=
 myconfig_mk_options=
 
 find_myconfig
-. $MOZ_MYCONFIG
 
-ac_echo_options
+if [ "$MOZ_MYCONFIG" ]
+then
+  . $MOZ_MYCONFIG
+  ac_echo_options
+fi