diff --git a/icu4c/source/test/intltest/tsmthred.cpp b/icu4c/source/test/intltest/tsmthred.cpp
index cb384af039f..8f33caba79e 100644
--- a/icu4c/source/test/intltest/tsmthred.cpp
+++ b/icu4c/source/test/intltest/tsmthred.cpp
@@ -1068,6 +1068,7 @@ void MultithreadTest::TestCollators()
     u_memcpy(lines[lineNum].buff, bufferU, buflen);
     lineNum++;
   }
+  fclose(testFile);