diff --git a/google-apis-core/lib/google/apis/core/base_service.rb b/google-apis-core/lib/google/apis/core/base_service.rb
index 416a7d449f8..22ee6553ce4 100644
--- a/google-apis-core/lib/google/apis/core/base_service.rb
+++ b/google-apis-core/lib/google/apis/core/base_service.rb
@@ -119,16 +119,16 @@ def universe_domain= new_ud
         end
 
         # Root URL (host/port) for the API
-        # @return [Addressable::URI]
+        # @return [Addressable::URI, String]
         attr_reader :root_url
 
         # Set the root URL.
         # If the given url includes a universe domain substitution, it is
         # resolved in the current universe domain
         #
-        # @param url_or_template [String] The URL, which can include a universe domain substitution
+        # @param url_or_template [Addressable::URI, String] The URL, which can include a universe domain substitution
         def root_url= url_or_template
-          if url_or_template.include? ENDPOINT_SUBSTITUTION
+          if url_or_template.is_a?(String) && url_or_template.include?(ENDPOINT_SUBSTITUTION)
             @root_url_template = url_or_template
             @root_url = url_or_template.gsub ENDPOINT_SUBSTITUTION, universe_domain
           else
diff --git a/google-apis-core/spec/google/apis/core/service_spec.rb b/google-apis-core/spec/google/apis/core/service_spec.rb
index 7650c85c36e..53167a12700 100644
--- a/google-apis-core/spec/google/apis/core/service_spec.rb
+++ b/google-apis-core/spec/google/apis/core/service_spec.rb
@@ -533,6 +533,11 @@
     expect(service_ud.root_url).to eql "https://endpoint1.mydomain5.com/"
   end
 
+  it "should support setting root url to Addressable::URI" do
+    service_ud.root_url = Addressable::URI.parse("https://endpoint1.mydomain5.com/")
+    expect(service_ud.root_url).to be_a(Addressable::URI)
+  end
+
   it "should support setting root url to a dynamic value" do
     service.universe_domain = "mydomain6.com"
     service.root_url = "https://endpoint2.$UNIVERSE_DOMAIN$/"