diff --git a/tests/include/test/psa_crypto_helpers.h b/tests/include/test/psa_crypto_helpers.h
index 9510c5f..3e356f9 100644
--- a/tests/include/test/psa_crypto_helpers.h
+++ b/tests/include/test/psa_crypto_helpers.h
@@ -43,6 +43,11 @@
  */
 void mbedtls_test_psa_purge_key_storage( void );
 
+/** Purge the in-memory cache of persistent keys recorded with
+ * #TEST_USES_KEY_ID.
+ */
+void mbedtls_test_psa_purge_key_cache( void );
+
 /** \def TEST_USES_KEY_ID
  *
  * Call this macro in a test function before potentially creating a
diff --git a/tests/src/psa_crypto_helpers.c b/tests/src/psa_crypto_helpers.c
index 500451e..f2222cb 100644
--- a/tests/src/psa_crypto_helpers.c
+++ b/tests/src/psa_crypto_helpers.c
@@ -63,6 +63,14 @@
         psa_destroy_persistent_key( key_ids_used_in_test[i] );
     num_key_ids_used = 0;
 }
+
+void mbedtls_test_psa_purge_key_cache( void )
+{
+    size_t i;
+    for( i = 0; i < num_key_ids_used; i++ )
+        psa_purge_key( key_ids_used_in_test[i] );
+}
+
 #endif /* MBEDTLS_PSA_CRYPTO_STORAGE_C */
 
 const char *mbedtls_test_helper_is_psa_leaking( void )
diff --git a/tests/suites/test_suite_psa_crypto_slot_management.function b/tests/suites/test_suite_psa_crypto_slot_management.function
index 2be1a73..7c55c71 100644
--- a/tests/suites/test_suite_psa_crypto_slot_management.function
+++ b/tests/suites/test_suite_psa_crypto_slot_management.function
@@ -86,6 +86,7 @@
         case INVALIDATE_BY_DESTROYING_WITH_SHUTDOWN:
         case INVALIDATE_BY_PURGING_WITH_SHUTDOWN:
             /* All keys must have been closed. */
+            mbedtls_test_psa_purge_key_cache( );
             PSA_DONE( );
             break;
         case INVALIDATE_BY_SHUTDOWN: