diff --git a/tests/testutils.cpp b/tests/testutils.cpp
index c1653b6..7609f20 100644
--- a/tests/testutils.cpp
+++ b/tests/testutils.cpp
@@ -423,7 +423,7 @@ void TestApplication::readFallbackTestfilePathFromSrcRef()
             // check whether the referenced source directory contains a "testfiles" directory
 #ifdef PLATFORM_UNIX // directoryEntries() is not implemented under Windows so we can only to the check under UNIX
         bool hasTestfilesDir = false;
-        for (const string dir : directoryEntries(srcDirContent.data(), DirectoryEntryType::Directory)) {
+        for (const string &dir : directoryEntries(srcDirContent.data(), DirectoryEntryType::Directory)) {
             if (dir == "testfiles") {
                 hasTestfilesDir = true;
                 break;