diff --git a/tests/run-tests.py b/tests/run-tests.py
index 8e9bd84313..ca7941f626 100755
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -31,18 +31,20 @@ def base_path(*p):
 if os.name == "nt":
     CPYTHON3 = os.getenv("MICROPY_CPYTHON3", "python")
     MICROPYTHON = os.getenv("MICROPY_MICROPYTHON", base_path("../ports/windows/micropython.exe"))
+    # mpy-cross is only needed if --via-mpy command-line arg is passed
+    MPYCROSS = os.getenv("MICROPY_MPYCROSS", base_path("../mpy-cross/mpy-cross.exe"))
 else:
     CPYTHON3 = os.getenv("MICROPY_CPYTHON3", "python3")
     MICROPYTHON = os.getenv(
         "MICROPY_MICROPYTHON", base_path("../ports/unix/build-standard/micropython")
     )
+    # mpy-cross is only needed if --via-mpy command-line arg is passed
+    MPYCROSS = os.getenv("MICROPY_MPYCROSS", base_path("../mpy-cross/build/mpy-cross"))
 
 # Use CPython options to not save .pyc files, to only access the core standard library
 # (not site packages which may clash with u-module names), and improve start up time.
 CPYTHON3_CMD = [CPYTHON3, "-BS"]
 
-# mpy-cross is only needed if --via-mpy command-line arg is passed
-MPYCROSS = os.getenv("MICROPY_MPYCROSS", base_path("../mpy-cross/build/mpy-cross"))
 
 # For diff'ing test output
 DIFF = os.getenv("MICROPY_DIFF", "diff -u")