diff --git a/src/config.c b/src/config.c
index 1d81180b..8f3b81a1 100644
--- a/src/config.c
+++ b/src/config.c
@@ -616,8 +616,9 @@ void loadServerConfigFromString(char *config) {
             unsigned long long hard, soft;
             int soft_seconds;
 
-            if (class == -1) {
-                err = "Unrecognized client limit class";
+            if (class == -1 || class == CLIENT_TYPE_MASTER) {
+                err = "Unrecognized client limit class: the user specified "
+                "an invalid one, or 'master' which has no buffer limits.";
                 goto loaderr;
             }
             hard = memtoll(argv[2],NULL);
@@ -906,7 +907,8 @@ void configSetCommand(client *c) {
             long val;
 
             if ((j % 4) == 0) {
-                if (getClientTypeByName(v[j]) == -1) {
+                int class = getClientTypeByName(v[j]);
+                if (class == -1 || class == CLIENT_TYPE_MASTER) {
                     sdsfreesplitres(v,vlen);
                     goto badfmt;
                 }