diff --git a/include/psa/crypto_builtin_composites.h b/include/psa/crypto_builtin_composites.h
index 3b0f82a..780a6c5 100644
--- a/include/psa/crypto_builtin_composites.h
+++ b/include/psa/crypto_builtin_composites.h
@@ -62,7 +62,6 @@
 typedef struct
 {
     psa_algorithm_t alg;
-    unsigned int key_set : 1;
     unsigned int has_input : 1;
     unsigned int is_sign : 1;
     uint8_t mac_size;
@@ -78,7 +77,7 @@
     } ctx;
 } mbedtls_psa_mac_operation_t;
 
-#define MBEDTLS_PSA_MAC_OPERATION_INIT {0, 0, 0, 0, 0, {0}}
+#define MBEDTLS_PSA_MAC_OPERATION_INIT {0, 0, 0, 0, {0}}
 
 /*
  * BEYOND THIS POINT, TEST DRIVER DECLARATIONS ONLY.
diff --git a/library/psa_crypto_mac.c b/library/psa_crypto_mac.c
index d8e2293..7122ecd 100644
--- a/library/psa_crypto_mac.c
+++ b/library/psa_crypto_mac.c
@@ -246,7 +246,6 @@
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
 
     operation->alg = PSA_ALG_FULL_LENGTH_MAC( alg );
-    operation->key_set = 0;
     operation->has_input = 0;
     operation->is_sign = 0;
 
@@ -307,7 +306,6 @@
     }
 
     operation->alg = 0;
-    operation->key_set = 0;
     operation->has_input = 0;
     operation->is_sign = 0;
 
@@ -385,9 +383,7 @@
     }
 
 exit:
-    if( status == PSA_SUCCESS )
-        operation->key_set = 1;
-    else
+    if( status != PSA_SUCCESS )
         mac_abort( operation );
 
     return( status );
@@ -444,7 +440,7 @@
     const uint8_t *input,
     size_t input_length )
 {
-    if( ! operation->key_set )
+    if( operation->alg == 0 )
         return( PSA_ERROR_BAD_STATE );
     operation->has_input = 1;
 
@@ -476,9 +472,8 @@
                                          uint8_t *mac,
                                          size_t mac_size )
 {
-    if( ! operation->key_set )
+    if( operation->alg == 0 )
         return( PSA_ERROR_BAD_STATE );
-
     if( mac_size < operation->mac_size )
         return( PSA_ERROR_BUFFER_TOO_SMALL );