diff --git a/mkfile.py b/mkfile.py
old mode 100644
new mode 100755
index 208a2b1..5fc7a8b
--- a/mkfile.py
+++ b/mkfile.py
@@ -1,41 +1,41 @@
-#!/usr/bin/python3
-# -*- coding: utf-8 -*-
-import sys
-import datetime
-
-if len(sys.argv) != 2:
-    print("Usage: mkfile.py <filename>")
-    sys.exit(1)
-
-filename = sys.argv[1]
-
-# create header file
-with open(f"./include/solution/{filename.lower()}.h", "w") as f:
-    f.write("// This file is generated by mkfile.py\n")
-    f.write(f"// Date: {datetime.datetime.now().strftime('%Y-%m-%d')}\n\n")
-    f.write(f"#ifndef INC_{filename.upper()}_H\n")
-    f.write(f"#define INC_{filename.upper()}_H\n")
-    f.write("#ifdef __cplusplus\n")
-    f.write("extern \"C\"\n")
-    f.write("{\n")
-    f.write("#endif\n\n")
-    f.write("#ifdef __cplusplus\n")
-    f.write("}\n")
-    f.write("#endif\n")
-    f.write(f"#endif // INC_{filename.upper()}_H\n")
-    f.close()
-
-# create source file
-with open(f"./src/{filename.lower()}.c", "w") as f:
-    f.write("// This file is generated by mkfile.py\n")
-    f.write(f"// Date: {datetime.datetime.now().strftime('%Y-%m-%d')}\n\n")
-    f.write(f'#include <solution/{filename.lower()}.h>\n')
-    f.close()
-
-# create test file
-with open(f"./tests/test_{filename.lower()}.cpp", "w") as f:
-    f.write("// This file is generated by mkfile.py\n")
-    f.write(f"// Date: {datetime.datetime.now().strftime('%Y-%m-%d')}\n\n")
-    f.write(f'#include <solution/{filename.lower()}.h>\n')
-    f.write("#include <gtest/gtest.h>\n")
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+import sys
+import datetime
+
+if len(sys.argv) != 2:
+    print("Usage: mkfile.py <filename>")
+    sys.exit(1)
+
+filename = sys.argv[1]
+
+# create header file
+with open(f"./include/solution/{filename.lower()}.h", "w") as f:
+    f.write("// This file is generated by mkfile.py\n")
+    f.write(f"// Date: {datetime.datetime.now().strftime('%Y-%m-%d')}\n\n")
+    f.write(f"#ifndef INC_{filename.upper()}_H\n")
+    f.write(f"#define INC_{filename.upper()}_H\n")
+    f.write("#ifdef __cplusplus\n")
+    f.write("extern \"C\"\n")
+    f.write("{\n")
+    f.write("#endif\n\n")
+    f.write("#ifdef __cplusplus\n")
+    f.write("}\n")
+    f.write("#endif\n")
+    f.write(f"#endif // INC_{filename.upper()}_H\n")
+    f.close()
+
+# create source file
+with open(f"./src/{filename.lower()}.c", "w") as f:
+    f.write("// This file is generated by mkfile.py\n")
+    f.write(f"// Date: {datetime.datetime.now().strftime('%Y-%m-%d')}\n\n")
+    f.write(f'#include <solution/{filename.lower()}.h>\n')
+    f.close()
+
+# create test file
+with open(f"./tests/test_{filename.lower()}.cpp", "w") as f:
+    f.write("// This file is generated by mkfile.py\n")
+    f.write(f"// Date: {datetime.datetime.now().strftime('%Y-%m-%d')}\n\n")
+    f.write(f'#include <solution/{filename.lower()}.h>\n')
+    f.write("#include <gtest/gtest.h>\n")
     f.close()
\ No newline at end of file