diff --git a/Makefile b/Makefile
index 2c48920b8..ef7cb2a44 100644
--- a/Makefile
+++ b/Makefile
@@ -14,8 +14,9 @@ ifeq ($(IS_FACEBOOK_TREE),yes)
 endif
 
 BUILD_SYSTEMS_TESTS = \
-  assembly ck_analytics ck_imports clang_multiple_files clang_translation delete_results_dir \
-  fail_on_issue gradle javac linters make project_root_rel reactive utf8_in_procname
+  assembly ck_analytics ck_imports clang_multiple_files clang_translation clang_unknown_ext \
+  delete_results_dir fail_on_issue gradle javac linters make project_root_rel reactive \
+  utf8_in_procname
 ifneq ($(ANT),no)
 BUILD_SYSTEMS_TESTS += ant
 endif
diff --git a/infer/tests/build_systems/build_integration_tests.py b/infer/tests/build_systems/build_integration_tests.py
index 18277856f..8db324cc0 100755
--- a/infer/tests/build_systems/build_integration_tests.py
+++ b/infer/tests/build_systems/build_integration_tests.py
@@ -61,7 +61,6 @@ CODETOANALYZE_DIR = os.path.join(SCRIPT_DIR, 'codetoanalyze')
 EXPECTED_OUTPUTS_DIR = os.path.join(SCRIPT_DIR, 'expected_outputs')
 
 ALL_TESTS = [
-    'unknown_ext',
     'utf8_in_pwd',
     'waf',
 ]
@@ -408,11 +407,6 @@ class BuildIntegrationTest(unittest.TestCase):
             report_fname='utf8_in_pwd_make_report.json')
         shutil.rmtree(utf8_in_pwd_path, True) # remove copied dir
 
-    def test_unknown_extension(self):
-        test('unknown_ext', 'unknown extension',
-             CODETOANALYZE_DIR,
-             [{'compile': ['clang', '-x', 'c', '-c', 'hello.unknown_ext']}])
-
 
 if __name__ == '__main__':
     # hackish capturing of the arguments after '--'
diff --git a/infer/tests/build_systems/clang_unknown_ext/Makefile b/infer/tests/build_systems/clang_unknown_ext/Makefile
new file mode 100644
index 000000000..20f8b3891
--- /dev/null
+++ b/infer/tests/build_systems/clang_unknown_ext/Makefile
@@ -0,0 +1,21 @@
+# Copyright (c) 2016 - present Facebook, Inc.
+# All rights reserved.
+#
+# This source code is licensed under the BSD style license found in the
+# LICENSE file in the root directory of this source tree. An additional grant
+# of patent rights can be found in the PATENTS file in the same directory.
+
+TESTS_DIR = ../..
+
+ANALYZER = infer
+
+CLANG_OPTIONS = -x c -c
+INFER_OPTIONS = --project-root ../codetoanalyze
+INFERPRINT_OPTIONS = --issues-tests
+
+SOURCES = ../codetoanalyze/hello.unknown_ext
+
+include $(TESTS_DIR)/clang.make
+
+../codetoanalyze/hello.o: ../codetoanalyze/hello.unknown_ext
+	clang $(CLANG_OPTIONS) $< > $@
diff --git a/infer/tests/build_systems/clang_unknown_ext/issues.exp b/infer/tests/build_systems/clang_unknown_ext/issues.exp
new file mode 100644
index 000000000..c51d658ea
--- /dev/null
+++ b/infer/tests/build_systems/clang_unknown_ext/issues.exp
@@ -0,0 +1 @@
+hello.unknown_ext, test, 2, NULL_DEREFERENCE, [start of procedure test()]
diff --git a/infer/tests/build_systems/expected_outputs/unknown_ext_report.json b/infer/tests/build_systems/expected_outputs/unknown_ext_report.json
deleted file mode 100644
index ffc159855..000000000
--- a/infer/tests/build_systems/expected_outputs/unknown_ext_report.json
+++ /dev/null
@@ -1,7 +0,0 @@
-[
-  {
-    "bug_type": "NULL_DEREFERENCE",
-    "file": "hello.unknown_ext",
-    "procedure": "test"
-  }
-]
\ No newline at end of file