diff --git a/src/flow.c b/src/flow.c
index 4764aeb4fb..ac8541f11f 100644
--- a/src/flow.c
+++ b/src/flow.c
@@ -436,6 +436,11 @@ void FlowInitConfig(char quiet)
     /** set config values for memcap, prealloc and hash_size */
     if ((ConfGet("flow.memcap", &conf_val)) == 1)
     {
+        if (conf_val == NULL) {
+            SCLogError(SC_ERR_INVALID_YAML_CONF_ENTRY,"Invalid value for flow.memcap: NULL");
+	    exit(EXIT_FAILURE);
+        }
+
         if (ParseSizeStringU64(conf_val, &flow_config.memcap) < 0) {
             SCLogError(SC_ERR_SIZE_PARSE, "Error parsing flow.memcap "
                        "from conf file - %s.  Killing engine",
@@ -445,6 +450,11 @@ void FlowInitConfig(char quiet)
     }
     if ((ConfGet("flow.hash-size", &conf_val)) == 1)
     {
+        if (conf_val == NULL) {
+            SCLogError(SC_ERR_INVALID_YAML_CONF_ENTRY,"Invalid value for flow.hash-size: NULL");
+	    exit(EXIT_FAILURE);
+        }
+
         if (ByteExtractStringUint32(&configval, 10, strlen(conf_val),
                                     conf_val) > 0) {
             flow_config.hash_size = configval;
@@ -452,6 +462,11 @@ void FlowInitConfig(char quiet)
     }
     if ((ConfGet("flow.prealloc", &conf_val)) == 1)
     {
+        if (conf_val == NULL) {
+            SCLogError(SC_ERR_INVALID_YAML_CONF_ENTRY,"Invalid value for flow.prealloc: NULL");
+	    exit(EXIT_FAILURE);
+        }
+
         if (ByteExtractStringUint32(&configval, 10, strlen(conf_val),
                                     conf_val) > 0) {
             flow_config.prealloc = configval;