diff --git a/tests/stdio_test.cpp b/tests/stdio_test.cpp
index 65a942c..c237d6d 100644
--- a/tests/stdio_test.cpp
+++ b/tests/stdio_test.cpp
@@ -29,6 +29,7 @@
 #include <locale.h>
 
 #include <string>
+#include <thread>
 #include <vector>
 
 #include <android-base/file.h>
@@ -2577,3 +2578,24 @@
   ASSERT_LT(0, length);
   ASSERT_EQ("/proc/self/fd/2", std::string(path, length));
 }
+
+TEST(STDIO_TEST, fread_with_locked_file) {
+  // Reading an unbuffered/line-buffered file from one thread shouldn't block on
+  // files locked on other threads, even if it flushes some line-buffered files.
+  FILE* fp1 = fopen("/dev/zero", "r");
+  ASSERT_TRUE(fp1 != nullptr);
+  flockfile(fp1);
+
+  std::thread([] {
+    for (int mode : { _IONBF, _IOLBF }) {
+      FILE* fp2 = fopen("/dev/zero", "r");
+      ASSERT_TRUE(fp2 != nullptr);
+      setvbuf(fp2, nullptr, mode, 0);
+      ASSERT_EQ('\0', fgetc(fp2));
+      fclose(fp2);
+    }
+  }).join();
+
+  funlockfile(fp1);
+  fclose(fp1);
+}