diff --git a/src/tool_paramhlp.c b/src/tool_paramhlp.c
index 188d6a1da5..71c738594d 100644
--- a/src/tool_paramhlp.c
+++ b/src/tool_paramhlp.c
@@ -291,7 +291,7 @@ ParameterError proto2num(struct OperationConfig *config,
   char *buffer;
   const char *sep = ",";
   char *token;
-  char obuf[256];
+  char obuf[256] = "";
   size_t olen = sizeof(obuf);
   char *optr;
   struct sprotos const *pp;