diff --git a/c/tools/run_tests.py b/c/tools/run_tests.py
index e2c17ac..1aee5a4 100644
--- a/c/tools/run_tests.py
+++ b/c/tools/run_tests.py
@@ -5,12 +5,13 @@ Used by `make test-c` so the test runner works from any shell (cmd.exe,
 PowerShell, Git Bash, MSYS2) without a POSIX `for` loop. Each test binary
 is a positional argument.
 """
+import os
 import subprocess
 import sys
 
 failed = []
 for binary in sys.argv[1:]:
-    rc = subprocess.call([binary])
+    rc = subprocess.call([os.path.normpath(binary)])
     if rc != 0:
         failed.append(binary)
 if failed: