diff --git a/query_classifier/query_classifier.cc b/query_classifier/query_classifier.cc
index 91342a224..788f6e5c6 100644
--- a/query_classifier/query_classifier.cc
+++ b/query_classifier/query_classifier.cc
@@ -151,7 +151,7 @@ bool parse_query (
         THD*            thd;
         uint8_t*        data;
         size_t          len;
-        char*           query_str;
+        char*           query_str = NULL;
         parsing_info_t* pi;
         
         CHK_GWBUF(querybuf);
@@ -173,9 +173,9 @@ bool parse_query (
         /** Extract query and copy it to different buffer */
         data = (uint8_t*)GWBUF_DATA(querybuf);
         len = MYSQL_GET_PACKET_LEN(data)-1; /*< distract 1 for packet type byte */        
-        query_str = (char *)malloc(len+1);
         
-        if (query_str == NULL)
+        
+        if (len < 1 || (query_str = (char *)malloc(len+1)) == NULL)
         {
                 /** Free parsing info data */
                 parsing_info_done(pi);
diff --git a/server/core/dcb.c b/server/core/dcb.c
index f66bc5c06..f8332de22 100644
--- a/server/core/dcb.c
+++ b/server/core/dcb.c
@@ -1776,11 +1776,12 @@ static bool dcb_set_state_nomutex(
  * @param dcb		The DCB to write buffer
  * @param buf		Buffer to write
  * @param nbytes	Number of bytes to write
+ * @return Number of written bytes
  */
 int
 gw_write(DCB *dcb, const void *buf, size_t nbytes)
 {
-        int w;
+        int w = 0;
 	int fd = dcb->fd;
 #if defined(FAKE_CODE)                
         if (fd > 0 && dcb_fake_write_errno[fd] != 0) 
diff --git a/server/core/modutil.c b/server/core/modutil.c
index ff031c8cf..5824de9e2 100644
--- a/server/core/modutil.c
+++ b/server/core/modutil.c
@@ -234,7 +234,7 @@ modutil_get_query(GWBUF *buf)
         uint8_t*           packet;
         mysql_server_cmd_t packet_type;
         size_t             len;
-        char*              query_str;
+        char*              query_str = NULL;
         
         packet = GWBUF_DATA(buf);
         packet_type = packet[4];
@@ -252,7 +252,7 @@ modutil_get_query(GWBUF *buf)
                         
                 case MYSQL_COM_QUERY:
                         len = MYSQL_GET_PACKET_LEN(packet)-1; /*< distract 1 for packet type byte */        
-                        if ((query_str = (char *)malloc(len+1)) == NULL)
+                        if (len < 1 || (query_str = (char *)malloc(len+1)) == NULL)
                         {
                                 goto retblock;
                         }
@@ -262,7 +262,7 @@ modutil_get_query(GWBUF *buf)
                         
                 default:
                         len = strlen(STRPACKETTYPE(packet_type))+1;
-                        if ((query_str = (char *)malloc(len+1)) == NULL)
+                        if (len < 1 || (query_str = (char *)malloc(len+1)) == NULL)
                         {
                                 goto retblock;
                         }
diff --git a/server/modules/routing/readwritesplit/readwritesplit.c b/server/modules/routing/readwritesplit/readwritesplit.c
index 3d53867d8..8668afbd4 100644
--- a/server/modules/routing/readwritesplit/readwritesplit.c
+++ b/server/modules/routing/readwritesplit/readwritesplit.c
@@ -3807,7 +3807,8 @@ static bool execute_sescmd_in_backend(
 			tmpbuf = scur->scmd_cur_cmd->my_sescmd_buf;
 			qlen = MYSQL_GET_PACKET_LEN((unsigned char*)tmpbuf->start);
 			memset(data->db,0,MYSQL_DATABASE_MAXLEN+1);
-			strncpy(data->db,tmpbuf->start+5,qlen - 1);			
+			if(qlen > 0)
+				strncpy(data->db,tmpbuf->start+5,qlen - 1);			
 		}
 		/** Fallthrough */
 		case MYSQL_COM_QUERY: