diff --git a/coders/xbm.c b/coders/xbm.c
index e952bfb..73d2f77 100644
--- a/coders/xbm.c
+++ b/coders/xbm.c
@@ -158,7 +158,7 @@
       break;
     value*=16;
     c&=0xff;
-    if (value > (INT_MAX-hex_digits[c]))
+    if (value > (unsigned int) (INT_MAX-hex_digits[c]))
       break;
     value+=hex_digits[c];
     c=ReadBlobByte(image);