diff --git a/scripts/mbedtls_dev/build_tree.py b/scripts/mbedtls_dev/build_tree.py
index 14790fc9c..ec67e4cdf 100644
--- a/scripts/mbedtls_dev/build_tree.py
+++ b/scripts/mbedtls_dev/build_tree.py
@@ -22,16 +22,23 @@ def looks_like_mbedtls_root(path: str) -> bool:
 def looks_like_root(path: str) -> bool:
     return looks_like_tf_psa_crypto_root(path) or looks_like_mbedtls_root(path)
 
-def crypto_core_directory(root: Optional[str] = None) -> str:
+def crypto_core_directory(root: Optional[str] = None, relative: Optional[bool] = False) -> str:
     """
     Return the path of the directory containing the PSA crypto core
     for either TF-PSA-Crypto or Mbed TLS.
+
+    Returns either the full path or relative path depending on the
+    "relative" boolean argument.
     """
     if root is None:
         root = guess_project_root()
     if looks_like_tf_psa_crypto_root(root):
+        if relative:
+            return "core"
         return os.path.join(root, "core")
     elif looks_like_mbedtls_root(root):
+        if relative:
+            return "library"
         return os.path.join(root, "library")
     else:
         raise Exception('Neither Mbed TLS nor TF-PSA-Crypto source tree found')
diff --git a/tests/scripts/test_psa_compliance.py b/tests/scripts/test_psa_compliance.py
index 984ddf3e1..57e4fbd52 100755
--- a/tests/scripts/test_psa_compliance.py
+++ b/tests/scripts/test_psa_compliance.py
@@ -51,7 +51,7 @@ def main(library_build_dir: str):
     in_tf_psa_crypto_repo = build_tree.looks_like_tf_psa_crypto_root(root_dir)
 
     crypto_name = build_tree.crypto_library_filename(root_dir)
-    library_subdir = build_tree.crypto_core_directory(root_dir)
+    library_subdir = build_tree.crypto_core_directory(root_dir, relative = True)
 
     crypto_lib_filename = (library_build_dir + '/' +
                            library_subdir + '/' +