diff --git a/dvc/config.py b/dvc/config.py
index f103c03b0..c6323c2b7 100644
--- a/dvc/config.py
+++ b/dvc/config.py
@@ -165,6 +165,9 @@ class Config(dict):
         with open(config_file, "w+", encoding="utf-8"):
             return Config(dvc_dir)
 
+    def merge(self, config):
+        merge(self, config)
+
     def load(
         self,
         validate: bool = True,
diff --git a/dvc/repo/fetch.py b/dvc/repo/fetch.py
index 034f2a3e3..2157ef6c5 100644
--- a/dvc/repo/fetch.py
+++ b/dvc/repo/fetch.py
@@ -48,7 +48,7 @@ def _collect_indexes(  # noqa: PLR0913
         all_commits=all_commits,
     ):
         try:
-            repo.config.update(config)
+            repo.config.merge(config)
 
             idx = repo.index.targets_view(
                 targets,