diff --git a/sapin.py b/sapin.py
index 18456df..4f25b9c 100644
--- a/sapin.py
+++ b/sapin.py
@@ -42,7 +42,7 @@ def sapin(fir_width):
 def slash():
     try:
         fir_width = int(request.args.get("n"))
-    except TypeError:
+    except (TypeError, ValueError):
         return (
             "Give an `n` query string as an integer, like <a href='/?n=10'>/?n=10</a>."
         )