diff --git a/unittest/testing/utils.h b/unittest/testing/utils.h
index c76b37872a..730c6fdb44 100644
--- a/unittest/testing/utils.h
+++ b/unittest/testing/utils.h
@@ -10,14 +10,12 @@
 
    See the README file in the top-level LAMMPS directory.
 ------------------------------------------------------------------------- */
-#ifndef TEST_EXTENSIONS__H
-#define TEST_EXTENSIONS__H
+#ifndef LMP_TESTING_UTILS_H
+#define LMP_TESTING_UTILS_H
 
 #include <fstream>
 #include <iostream>
 #include <string>
-#include <sys/stat.h>
-#include <sys/types.h>
 #include <vector>
 
 static void delete_file(const std::string &filename)
@@ -65,8 +63,8 @@ static std::vector<std::string> read_lines(const std::string &filename)
 
 static bool file_exists(const std::string &filename)
 {
-    struct stat result;
-    return stat(filename.c_str(), &result) == 0;
+    std::ifstream infile(filename);
+    return infile.good();
 }
 
 #define ASSERT_FILE_EXISTS(NAME) ASSERT_TRUE(file_exists(NAME))