diff --git a/MagickCore/xwindow.c b/MagickCore/xwindow.c
index a4cb182..2dc7387 100644
--- a/MagickCore/xwindow.c
+++ b/MagickCore/xwindow.c
@@ -3051,6 +3051,10 @@
   Colormap
     colormap;
 
+  extern const char
+    BorderColor[],
+    ForegroundColor[];
+
   register ssize_t
     i;
 
@@ -3478,6 +3482,10 @@
     *directory,
     *resource_value;
 
+  extern const char
+    BorderColor[],
+    ForegroundColor[];
+
   /*
     Initialize resource info fields.
   */