diff --git a/src/redis.c b/src/redis.c
index b781ebd6..c87b9ac2 100644
--- a/src/redis.c
+++ b/src/redis.c
@@ -2207,7 +2207,13 @@ int processCommand(redisClient *c) {
      * is returning an error. */
     if (server.maxmemory) {
         int retval = freeMemoryIfNeeded();
-        if ((c->cmd->flags & REDIS_CMD_DENYOOM) && retval == REDIS_ERR) {
+        /* freeMemoryIfNeeded may flush slave output buffers. This may result
+         * into a slave, that may be the active client, to be freed. */
+        if (server.current_client == NULL) return REDIS_ERR;
+
+        /* It was impossible to free enough memory, and the command the client
+         * is trying to execute is denied during OOM conditions? Error. */
+        if ((c->cmd->flags & CMD_DENYOOM) && retval == REDIS_ERR) {
             flagTransaction(c);
             addReply(c, shared.oomerr);
             return REDIS_OK;