diff --git a/src/server/slavefuncs.c b/src/server/slavefuncs.c
--- a/src/server/slavefuncs.c
+++ b/src/server/slavefuncs.c
@@ -804,12 +804,12 @@ int slaveBenchmark(char *datadir, int *b
 
   time(&startTime);
 
-  char buf[10];
+  char buf[20];
   struct execio *testrem;
   size_t readlen;
 
   ret = execio_open(&testrem, command, cmd);
-  buf[20] = '\0';
+  buf[19] = '\0';
   while(!execio_read(testrem, buf, 20, &readlen))
     {
       if(readlen > 20) {