diff --git a/src/iperf_api.c b/src/iperf_api.c
index 8a6635222..2d8d4ed42 100644
--- a/src/iperf_api.c
+++ b/src/iperf_api.c
@@ -2801,7 +2801,7 @@ JSON_read(int fd)
      */
     rc = Nread(fd, (char*) &nsize, sizeof(nsize), Ptcp);
     hsize = ntohl(nsize);
-    if (rc == sizeof(nsize) && hsize <= MAX_PARAMS_JSON_STRING) {
+    if (rc == sizeof(nsize) && hsize > 0 && hsize <= MAX_PARAMS_JSON_STRING) {
 	/* Allocate a buffer to hold the JSON */
 	strsize = hsize + 1;              /* +1 for trailing NULL */
 	if (strsize) {