diff --git a/programs/psa/aead_cipher_psa.c b/programs/psa/aead_cipher_psa.c
index 301701c..ef73e7a 100644
--- a/programs/psa/aead_cipher_psa.c
+++ b/programs/psa/aead_cipher_psa.c
@@ -88,7 +88,7 @@
     do {                    \
         ret = code;         \
         if( ret != 0 ) {    \
-            printf( "%s:%03d: ret = -0x%04x\n", __func__, __LINE__, -ret ); \
+            printf( "%s:%03d: ret = -0x%04x\n", __func__, __LINE__, (unsigned) -ret ); \
             goto exit;      \
         }                   \
     } while( 0 )
diff --git a/programs/psa/hmac_md_psa.c b/programs/psa/hmac_md_psa.c
index cde78f1..0a9a02b 100644
--- a/programs/psa/hmac_md_psa.c
+++ b/programs/psa/hmac_md_psa.c
@@ -159,7 +159,7 @@
     printf( "MD\n" );
     int ret = md();
     if( ret != 0 )
-        printf( "ret = %d (-0x%04x)\n", ret, -ret );
+        printf( "ret = %d (-0x%04x)\n", ret, (unsigned) -ret );
 
     psa_status_t status = psa_crypto_init();
     if( status != PSA_SUCCESS )