diff --git a/tests/cmp b/tests/cmp
index 0c7fa15..b8e4864 100755
--- a/tests/cmp
+++ b/tests/cmp
@@ -247,7 +247,7 @@ cmp -i 1000 -n $big j1 j2 || fail=1
 
 rm -f a b
 if timeout 0.1 true && truncate -s 14T a && truncate -s 15T b; then
-  returns_ 1 timeout 0.1 cmp a b >/dev/null || fail=1
+  returns_ 1 timeout 0.4 cmp a b >/dev/null || fail=1
 fi
 rm -f a b