diff --git a/lib/xlib/color.c b/lib/xlib/color.c
index d8f4f2b..63c57fa 100644
--- a/lib/xlib/color.c
+++ b/lib/xlib/color.c
@@ -37,7 +37,7 @@ static int Color_Equal (Object x, Object y) {
     return p->red == q->red && p->green == q->green && p->blue == q->blue;
 }
 
-Generic_Print (Color, "#[color %lu]", POINTER(x))
+Generic_Print (Color, "#[color %lu]", (unsigned int)(uintptr_t)POINTER(x))
 
 Object Make_Color (unsigned int r, unsigned int g, unsigned int b) {
     Object c;
diff --git a/lib/xlib/display.c b/lib/xlib/display.c
index 77a41fd..12fc568 100644
--- a/lib/xlib/display.c
+++ b/lib/xlib/display.c
@@ -43,7 +43,8 @@ Generic_Equal (Display, DISPLAY, dpy)
 
 static int Display_Print (Object d, Object port,
                           int raw, int depth, int length) {
-    Printf (port, "#[display %lu %s]", (unsigned)DISPLAY(d)->dpy,
+    Printf (port, "#[display %lu %s]",
+        (unsigned long)(uintptr_t)DISPLAY(d)->dpy,
         DisplayString (DISPLAY(d)->dpy));
     return 0;
 }
diff --git a/lib/xlib/gcontext.c b/lib/xlib/gcontext.c
index f332e58..9162c8d 100644
--- a/lib/xlib/gcontext.c
+++ b/lib/xlib/gcontext.c
@@ -36,7 +36,7 @@ Generic_Predicate (Gc)
 
 Generic_Equal_Dpy (Gc, GCONTEXT, gc)
 
-Generic_Print (Gc, "#[gcontext %lu]", GCONTEXT(x)->gc)
+Generic_Print (Gc, "#[gcontext %lu]", (unsigned int)(uintptr_t)GCONTEXT(x)->gc)
 
 Generic_Get_Display (Gc, GCONTEXT)