diff --git a/oss-internship-2020/libpng/README.md b/oss-internship-2020/libpng/README.md
index c649592..f71b776 100644
--- a/oss-internship-2020/libpng/README.md
+++ b/oss-internship-2020/libpng/README.md
@@ -38,7 +38,8 @@ output: `images/rgbtobgr_red_ball.png`
 
 
 #### Tests:
-You should add `-DLIBPNG_SAPI_ENABLE_TESTS=ON` to use tests and run:
+You should add `-DLIBPNG_SAPI_ENABLE_TESTS=ON` to use tests and do:
 ```
-./tests/tests
+cd tests
+ctest .
 ```
diff --git a/oss-internship-2020/libpng/tests/CMakeLists.txt b/oss-internship-2020/libpng/tests/CMakeLists.txt
index 8feaad7..ea4af40 100644
--- a/oss-internship-2020/libpng/tests/CMakeLists.txt
+++ b/oss-internship-2020/libpng/tests/CMakeLists.txt
@@ -32,5 +32,4 @@ target_link_libraries(tests PRIVATE
   sapi::sapi
 )
 
-gtest_discover_tests(tests)
-
+gtest_discover_tests(tests PROPERTIES ENVIRONMENT "TEST_SRCDIR=${PROJECT_SOURCE_DIR}")
diff --git a/oss-internship-2020/libpng/tests/basic_test.cc b/oss-internship-2020/libpng/tests/basic_test.cc
index 4c4f97d..6b6b6d2 100644
--- a/oss-internship-2020/libpng/tests/basic_test.cc
+++ b/oss-internship-2020/libpng/tests/basic_test.cc
@@ -28,7 +28,7 @@ using ::testing::Eq;
 using ::testing::IsTrue;
 
 TEST(SandboxTest, ReadWrite) {
-  std::string infile = GetTestFilePath("pngtest.png");
+  std::string infile = GetFilePath("pngtest.png");
 
   absl::StatusOr<std::string> status_or_path =
       sandbox2::CreateNamedTempFileAndClose("output.png");
diff --git a/oss-internship-2020/libpng/tests/extended_test.cc b/oss-internship-2020/libpng/tests/extended_test.cc
index deda14e..a2e67e3 100644
--- a/oss-internship-2020/libpng/tests/extended_test.cc
+++ b/oss-internship-2020/libpng/tests/extended_test.cc
@@ -191,8 +191,8 @@ void WritePng(LibPNGApi& api, absl::string_view outfile, Data& data) {
 }
 
 TEST(SandboxTest, ReadModifyWrite) {
-  std::string infile = GetTestFilePath("red_ball.png");
-  std::string outfile = GetTestFilePath("test_output.png");
+  std::string infile = GetFilePath("red_ball.png");
+  std::string outfile = GetFilePath("test_output.png");
 
   LibPNGSapiSandbox sandbox;
   ASSERT_THAT(sandbox.Init(), IsOk());
diff --git a/oss-internship-2020/libpng/tests/helper.cc b/oss-internship-2020/libpng/tests/helper.cc
index b349c6b..84ab30c 100644
--- a/oss-internship-2020/libpng/tests/helper.cc
+++ b/oss-internship-2020/libpng/tests/helper.cc
@@ -13,28 +13,12 @@
 // limitations under the License.
 
 #include "helper.h"  // NOLINT(build/include)
+
 #include "../sandboxed.h"  // NOLINT(build/include)
-#include "sandboxed_api/sandbox2/util/fileops.h"
 #include "sandboxed_api/sandbox2/util/path.h"
 
-std::string GetImagesFolder() {
-  std::string cwd = sandbox2::file_util::fileops::GetCWD();
-  auto find = cwd.rfind("/build");
-  if (find == std::string::npos) {
-    LOG(ERROR) << "Something went wrong: CWD don't contain build dir. "
-               << "Please run tests from build dir, path might be incorrect\n";
+std::string GetSourcePath() { return getenv("TEST_SRCDIR"); }
 
-    return sandbox2::file::JoinPath(cwd, "images");
-  }
-
-  return sandbox2::file::JoinPath(cwd.substr(0, find), "images");
+std::string GetFilePath(absl::string_view filename) {
+  return sandbox2::file::JoinPath(GetSourcePath(), "images", filename);
 }
-
-std::string GetTestFilePath(const std::string& filename) {
-  static std::string* images_folder_path = nullptr;
-  if (!images_folder_path) {
-    images_folder_path = new std::string(GetImagesFolder());
-  }
-  return sandbox2::file::JoinPath(*images_folder_path, filename);
-}
-
diff --git a/oss-internship-2020/libpng/tests/helper.h b/oss-internship-2020/libpng/tests/helper.h
index 9590f61..7a2a97c 100644
--- a/oss-internship-2020/libpng/tests/helper.h
+++ b/oss-internship-2020/libpng/tests/helper.h
@@ -12,7 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <string>
-
-std::string GetTestFilePath(const std::string& filename);
+#include "absl/strings/str_join.h"
 
+std::string GetFilePath(absl::string_view filename);