diff --git a/fifteen.c b/fifteen.c
index 211f06d..2ba25af 100644
--- a/fifteen.c
+++ b/fifteen.c
@@ -7,6 +7,7 @@
 #include <string.h>
 #include <assert.h>
 #include <ctype.h>
+#include <limits.h>
 #include <math.h>
 
 #include "puzzles.h"
@@ -138,6 +139,8 @@ static const char *validate_params(const game_params *params, bool full)
 {
     if (params->w < 2 || params->h < 2)
 	return "Width and height must both be at least two";
+    if (params->w > INT_MAX / params->h)
+        return "Width times height must not be unreasonably large";
 
     return NULL;
 }