diff --git a/Flowd-perl/Flowd.xs b/Flowd-perl/Flowd.xs
index 3b72d9b..1f0a5c0 100644
--- a/Flowd-perl/Flowd.xs
+++ b/Flowd-perl/Flowd.xs
@@ -70,7 +70,7 @@ void deserialise(...)
 		buf = (char *)SvPV(ST(0), len);
 		r = store_flow_deserialise(buf, len, &flow, ebuf, sizeof(ebuf));
 		if (r != STORE_ERR_OK)
-			croak(ebuf);
+			croak("%s", ebuf);
 
 		fields = ntohl(flow.hdr.fields);