diff --git a/libgksu/libgksu.SlackBuild b/libgksu/libgksu.SlackBuild
index e678536..19e55cb 100644
--- a/libgksu/libgksu.SlackBuild
+++ b/libgksu/libgksu.SlackBuild
@@ -85,7 +85,7 @@ if [ "$ARCH" = "x86_64" ]; then
   patch -p1 < $CWD/libgksu-2.0.12-x86_64-path.diff
 fi
 
-LDFLAGS="-lgtk" \
+LDFLAGS="-lgtk -lX11" \
 CFLAGS="$SLKCFLAGS" \
 CXXFLAGS="$SLKCFLAGS" \
 ./configure \