diff --git a/src/debug.c b/src/debug.c
index 30c51a1b0..36cef5625 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -600,12 +600,14 @@ NULL
         robj *key, *val;
         char buf[128];
 
-        if (getLongFromObjectOrReply(c, c->argv[2], &keys, NULL) != C_OK)
+        if (getPositiveLongFromObjectOrReply(c, c->argv[2], &keys, NULL) != C_OK)
             return;
+
         dictExpand(c->db->dict,keys);
         long valsize = 0;
-        if ( c->argc == 5 && getLongFromObjectOrReply(c, c->argv[4], &valsize, NULL) != C_OK ) 
+        if ( c->argc == 5 && getPositiveLongFromObjectOrReply(c, c->argv[4], &valsize, NULL) != C_OK ) 
             return;
+
         for (j = 0; j < keys; j++) {
             snprintf(buf,sizeof(buf),"%s:%lu",
                 (c->argc == 3) ? "key" : (char*)c->argv[3]->ptr, j);
diff --git a/src/object.c b/src/object.c
index 1b8852f18..eef5e6d9e 100644
--- a/src/object.c
+++ b/src/object.c
@@ -730,6 +730,23 @@ int getLongFromObjectOrReply(client *c, robj *o, long *target, const char *msg)
     return C_OK;
 }
 
+int getRangeLongFromObjectOrReply(client *c, robj *o, long min, long max, long *target, const char *msg) {
+    if (getLongFromObjectOrReply(c, o, target, msg) != C_OK) return C_ERR;
+    if (*target < min || *target > max) {
+        if (msg != NULL) {
+            addReplyError(c,(char*)msg);
+        } else {
+            addReplyErrorFormat(c,"value is out of range, value must between %ld and %ld", min, max);
+        }
+        return C_ERR;
+    }
+    return C_OK;
+}
+
+int getPositiveLongFromObjectOrReply(client *c, robj *o, long *target, const char *msg) {
+    return getRangeLongFromObjectOrReply(c, o, 0, LONG_MAX, target, msg);
+}
+
 char *strEncoding(int encoding) {
     switch(encoding) {
     case OBJ_ENCODING_RAW: return "raw";
diff --git a/src/server.h b/src/server.h
index 5a37ad65b..ea6eb5f04 100644
--- a/src/server.h
+++ b/src/server.h
@@ -1838,6 +1838,8 @@ robj *createZsetZiplistObject(void);
 robj *createStreamObject(void);
 robj *createModuleObject(moduleType *mt, void *value);
 int getLongFromObjectOrReply(client *c, robj *o, long *target, const char *msg);
+int getPositiveLongFromObjectOrReply(client *c, robj *o, long *target, const char *msg);
+int getRangeLongFromObjectOrReply(client *c, robj *o, long min, long max, long *target, const char *msg);
 int checkType(client *c, robj *o, int type);
 int getLongLongFromObjectOrReply(client *c, robj *o, long long *target, const char *msg);
 int getDoubleFromObjectOrReply(client *c, robj *o, double *target, const char *msg);