diff --git a/tests/scripts/generate_psa_wrappers.py b/tests/scripts/generate_psa_wrappers.py
index 4271fe6..fbc598f 100755
--- a/tests/scripts/generate_psa_wrappers.py
+++ b/tests/scripts/generate_psa_wrappers.py
@@ -143,6 +143,8 @@
         """Whether the specified buffer argument to a PSA function should be copied.
         """
         # Proof-of-concept: just instrument one function for now
+        if function_name == 'psa_cipher_encrypt':
+            return True
         if function_name == 'psa_import_key' or function_name == 'psa_export_key' or function_name == 'psa_export_public_key':
             return True
         if function_name in ('psa_sign_message',