diff --git a/src/modules/pdb/common.h b/src/modules/pdb/common.h
index 1ba16cdf98f..7c52c97ce0f 100644
--- a/src/modules/pdb/common.h
+++ b/src/modules/pdb/common.h
@@ -35,7 +35,8 @@
 #define OTHER_CARRIERID 1000
 #define MAX_CARRIERID 1000
 #define NULL_CARRIERID -1001
-#define PAYLOADSIZE 256
+/* hdr size + PAYLOADSIZE must add to 255 (uint8_t pdb_hdr.length) */
+#define PAYLOADSIZE 249
 
 
 #define IS_VALID_PDB_CARRIERID(id) ((id>=MIN_PDB_CARRIERID) && (id<=MAX_PDB_CARRIERID))
diff --git a/src/modules/pdb/pdb.c b/src/modules/pdb/pdb.c
index 8f2f80c3269..eb59656734c 100644
--- a/src/modules/pdb/pdb.c
+++ b/src/modules/pdb/pdb.c
@@ -145,7 +145,7 @@ static struct server_list_t *server_list;
 /* debug function for the new client <-> server protocol */
 static void pdb_msg_dbg(struct pdb_msg msg, char *dbg_msg) {
     int i;
-    char buf[PAYLOADSIZE];
+    char buf[PAYLOADSIZE * 3 + 1];
     char *ptr = buf;
 
     for (i = 0; i < msg.hdr.length - sizeof(msg.hdr); i++) {
@@ -265,7 +265,7 @@ static int pdb_query(struct sip_msg *_msg, struct multiparam_t *_number, struct
 
 	/* prepare request */
 	reqlen = number.len + 1; /* include null termination */
-	if (reqlen > sizeof(struct pdb_bdy)) {
+	if (reqlen > PAYLOADSIZE) {
 		LM_ERR("number too long '%.*s'.\n", number.len, number.s);
 		return -1;
 	}
@@ -305,6 +305,7 @@ static int pdb_query(struct sip_msg *_msg, struct multiparam_t *_number, struct
             break;
     }
 
+	memset(&msg, 0, sizeof(struct pdb_msg));
 	/* wait for response */
 	for (;;) {
 		if (gettimeofday(&tnow, NULL) != 0) {