diff --git a/src/test/cpp/util/file_test.cc b/src/test/cpp/util/file_test.cc
index 49c52c0..fa379f5 100644
--- a/src/test/cpp/util/file_test.cc
+++ b/src/test/cpp/util/file_test.cc
@@ -41,11 +41,12 @@
     ASSERT_TRUE(pipe.get()->Send(" world", 6));
   });
 
+  // Wait for all data to be fully written to the pipe.
+  writer_thread.join();
+
   ASSERT_EQ(3, pipe.get()->Receive(buffer, 3));
   ASSERT_EQ(5, pipe.get()->Receive(buffer + 3, 5));
   ASSERT_EQ(3, pipe.get()->Receive(buffer + 8, 40));
-  writer_thread.join();
-
   ASSERT_EQ(0, strncmp(buffer, "hello world", 11));
 }