diff --git a/bridges.c b/bridges.c
index de95afe..ec25cab 100644
--- a/bridges.c
+++ b/bridges.c
@@ -72,6 +72,7 @@
 #include <string.h>
 #include <assert.h>
 #include <ctype.h>
+#include <limits.h>
 #include <math.h>
 
 #include "puzzles.h"
@@ -803,6 +804,8 @@ static const char *validate_params(const game_params *params, bool full)
 {
     if (params->w < 3 || params->h < 3)
         return "Width and height must be at least 3";
+    if (params->w > INT_MAX / params->h)
+        return "Width times height must not be unreasonably large";
     if (params->maxb < 1 || params->maxb > MAX_BRIDGES)
         return "Too many bridges.";
     if (full) {