diff --git a/mozilla/configure b/mozilla/configure
index a1b324c1dbd..0939b5a9487 100755
--- a/mozilla/configure
+++ b/mozilla/configure
@@ -10025,7 +10025,7 @@ if test "${enable_extensions+set}" = set; then
         MOZ_EXTENSIONS=""
     elif test "$option" = "default"; then
         MOZ_EXTENSIONS="$MOZ_EXTENSIONS $MOZ_EXTENSIONS_DEFAULT"
-    elif test `echo "$option" | grep -c ^-`; then
+    elif test `echo "$option" | grep -c ^-` != 0; then
         option=`echo $option | sed 's/^-//'`
         MOZ_EXTENSIONS=`echo "$MOZ_EXTENSIONS" | sed "s/ ${option}//"`
     else