diff --git a/scripts/config.py b/scripts/config.py
index 77a09ad9c5..d2de7a7233 100755
--- a/scripts/config.py
+++ b/scripts/config.py
@@ -593,9 +593,11 @@ class CryptoConfigFile(ConfigFile):
     # Temporary, while Mbed TLS does not just rely on the TF-PSA-Crypto
     # build system to build its crypto library. When it does, the
     # condition can just be removed.
-    _path_in_tree = 'include/psa/crypto_config.h' \
-                    if os.path.isfile('include/psa/crypto_config.h') else \
-                    'tf-psa-crypto/include/psa/crypto_config.h'
+    _path_in_tree = ('include/psa/crypto_config.h'
+                     if not os.path.isdir(os.path.join(os.path.dirname(__file__),
+                                                       os.pardir,
+                                                       'tf-psa-crypto')) else
+                     'tf-psa-crypto/include/psa/crypto_config.h')
     default_path = [_path_in_tree,
                     os.path.join(os.path.dirname(__file__),
                                  os.pardir,