diff --git a/sixteen.c b/sixteen.c
index aa10f4a..7c9e7aa 100644
--- a/sixteen.c
+++ b/sixteen.c
@@ -9,6 +9,7 @@
 #include <string.h>
 #include <assert.h>
 #include <ctype.h>
+#include <limits.h>
 #include <math.h>
 
 #include "puzzles.h"
@@ -173,6 +174,8 @@ 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;
 }