diff --git a/src/tools/pkcs11-tool.c b/src/tools/pkcs11-tool.c
index 92c8d8a5..11d5e52d 100644
--- a/src/tools/pkcs11-tool.c
+++ b/src/tools/pkcs11-tool.c
@@ -775,7 +775,7 @@ int main(int argc, char * argv[])
 			opt_sig_format = optarg;
 			break;
 		case 't':
-			need_session |= NEED_SESSION_RO;
+			need_session |= NEED_SESSION_RW;
 			do_test = 1;
 			action_count++;
 			break;