diff --git a/programs/x509/cert_write.c b/programs/x509/cert_write.c
index 94dfa1d..8e4951e 100644
--- a/programs/x509/cert_write.c
+++ b/programs/x509/cert_write.c
@@ -571,6 +571,7 @@
 
     printf( " ok\n" );
 
+#if defined(POLARSSL_SHA1_C)
     printf( "  . Adding the Subject Key Identifier ..." );
     fflush( stdout );
 
@@ -596,6 +597,7 @@
     }
 
     printf( " ok\n" );
+#endif /* POLARSSL_SHA1_C */
 
     if( opt.key_usage )
     {