diff --git a/alts/src/main/java/io/grpc/alts/GoogleDefaultChannelBuilder.java b/alts/src/main/java/io/grpc/alts/GoogleDefaultChannelBuilder.java
index 8a5ece69a2..0c66b99af1 100644
--- a/alts/src/main/java/io/grpc/alts/GoogleDefaultChannelBuilder.java
+++ b/alts/src/main/java/io/grpc/alts/GoogleDefaultChannelBuilder.java
@@ -60,6 +60,17 @@ public final class GoogleDefaultChannelBuilder
     delegate = NettyChannelBuilder.forTarget(target);
     InternalNettyChannelBuilder.setProtocolNegotiatorFactory(
         delegate(), new ProtocolNegotiatorFactory());
+    @Nullable CallCredentials credentials = null;
+    Status status = Status.OK;
+    try {
+      credentials = MoreCallCredentials.from(GoogleCredentials.getApplicationDefault());
+    } catch (IOException e) {
+      status =
+          Status.UNAUTHENTICATED
+              .withDescription("Failed to get Google default credentials")
+              .withCause(e);
+    }
+    delegate().intercept(new GoogleDefaultInterceptor(credentials, status));
   }
 
   /** "Overrides" the static method in {@link ManagedChannelBuilder}. */
@@ -77,21 +88,6 @@ public final class GoogleDefaultChannelBuilder
     return delegate;
   }
 
-  @Override
-  public ManagedChannel build() {
-    @Nullable CallCredentials credentials = null;
-    Status status = Status.OK;
-    try {
-      credentials = MoreCallCredentials.from(GoogleCredentials.getApplicationDefault());
-    } catch (IOException e) {
-      status =
-          Status.UNAUTHENTICATED
-              .withDescription("Failed to get Google default credentials")
-              .withCause(e);
-    }
-    return delegate().intercept(new GoogleDefaultInterceptor(credentials, status)).build();
-  }
-
   @VisibleForTesting
   GoogleDefaultProtocolNegotiator getProtocolNegotiatorForTest() {
     return negotiatorForTest;