diff --git a/prost-build/src/config.rs b/prost-build/src/config.rs
index 0fafa8f6e..92d154da1 100644
--- a/prost-build/src/config.rs
+++ b/prost-build/src/config.rs
@@ -684,7 +684,6 @@ impl Config {
         S: AsRef<str>,
         D: AsRef<str>,
     {
-        self.type_name_domains.clear();
         for matcher in paths {
             self.type_name_domains
                 .insert(matcher.as_ref().to_string(), domain.as_ref().to_string());
diff --git a/tests/build.rs b/tests/build.rs
index 06c9e0472..1403a3e5e 100644
--- a/tests/build.rs
+++ b/tests/build.rs
@@ -165,6 +165,7 @@ fn main() {
     prost_build::Config::new()
         .enable_type_names()
         .type_name_domain([".type_names.Foo"], "tests")
+        .type_name_domain([".type_names.Qux"], "tests-cumulative")
         .compile_protos(&[src.join("type_names.proto")], includes)
         .unwrap();
 
diff --git a/tests/src/type_names.proto b/tests/src/type_names.proto
index 58c599d17..0b6b6f1be 100644
--- a/tests/src/type_names.proto
+++ b/tests/src/type_names.proto
@@ -8,4 +8,7 @@ message Foo {
 }
 
 message Baz {
-}
\ No newline at end of file
+}
+
+message Qux {
+}
diff --git a/tests/src/type_names.rs b/tests/src/type_names.rs
index 09fb41aa1..285dc50b4 100644
--- a/tests/src/type_names.rs
+++ b/tests/src/type_names.rs
@@ -18,4 +18,9 @@ fn valid_type_names() {
     assert_eq!("type_names", Baz::PACKAGE);
     assert_eq!("type_names.Baz", Baz::full_name());
     assert_eq!("/type_names.Baz", Baz::type_url());
+
+    assert_eq!("Qux", Qux::NAME);
+    assert_eq!("type_names", Qux::PACKAGE);
+    assert_eq!("type_names.Qux", Qux::full_name());
+    assert_eq!("tests-cumulative/type_names.Qux", Qux::type_url());
 }