diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index d53d6ee..a12b454 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -469,6 +469,9 @@
     if( slot->type == PSA_KEY_TYPE_NONE )
         return( PSA_ERROR_EMPTY_SLOT );
 
+    if( !( slot->policy.usage & PSA_KEY_USAGE_EXPORT ) )
+        return( PSA_ERROR_NOT_PERMITTED );
+
     if( PSA_KEY_TYPE_IS_RAW_BYTES( slot->type ) )
     {
         if( slot->data.raw.bytes > data_size )
@@ -1185,6 +1188,8 @@
         return( PSA_ERROR_EMPTY_SLOT );
     if( ! PSA_KEY_TYPE_IS_KEYPAIR( slot->type ) )
         return( PSA_ERROR_INVALID_ARGUMENT );
+    if( !( slot->policy.usage & PSA_KEY_USAGE_SIGN ) )
+        return( PSA_ERROR_NOT_PERMITTED );
 
 #if defined(MBEDTLS_RSA_C)
     if( slot->type == PSA_KEY_TYPE_RSA_KEYPAIR )