diff --git a/src/jobserver_test.cc b/src/jobserver_test.cc
index 2e2fc26e61..5e6d4c22f8 100644
--- a/src/jobserver_test.cc
+++ b/src/jobserver_test.cc
@@ -186,7 +186,15 @@ TEST(Jobserver, ParseNativeMakeFlagsValue) {
   Jobserver::Config config;
   std::string error;
 
-  // --jobserver-auth=R,W is not supported.
+#ifdef _WIN32
+  // --jobserver-auth=R,W is not supported on Windows.
+  config = {};
+  error.clear();
+  EXPECT_FALSE(Jobserver::ParseNativeMakeFlagsValue("--jobserver-auth=3,4",
+                                                    &config, &error));
+  EXPECT_EQ(error, "Pipe mode is not supported on Windows!");
+#else   // !_WIN32
+  // --jobserver-auth=R,W supported on Posix.
   config = {};
   error.clear();
   EXPECT_TRUE(Jobserver::ParseNativeMakeFlagsValue("--jobserver-auth=3,4",
@@ -194,6 +202,7 @@ TEST(Jobserver, ParseNativeMakeFlagsValue) {
   EXPECT_EQ(Jobserver::Config::kModePipe, config.mode);
   EXPECT_EQ(3, config.read_fd);
   EXPECT_EQ(4, config.write_fd);
+#endif  // !_WIN32
 
 #ifdef _WIN32
   // --jobserver-auth=NAME works on Windows.