diff --git a/t/cmdline-invalidcommand.txtar b/t/cmdline-invalidcommand.txtar
index f30dbe4..f1c0949 100644
--- a/t/cmdline-invalidcommand.txtar
+++ b/t/cmdline-invalidcommand.txtar
@@ -1,2 +1,2 @@
-exec testrpn 1 2 dumb
+! exec testrpn 1 2 dumb
 stdout 'unknown command or operator'
diff --git a/t/cmdline-short-stack.txtar b/t/cmdline-short-stack.txtar
index f3ce466..30ac14f 100644
--- a/t/cmdline-short-stack.txtar
+++ b/t/cmdline-short-stack.txtar
@@ -1,2 +1,2 @@
-exec testrpn 4 +
+! exec testrpn 4 +
 stdout 'stack doesn''t provide enough arguments'
diff --git a/t/cmdlinecalc-divzero.txtar b/t/cmdlinecalc-divzero.txtar
index 411c636..bc32f83 100644
--- a/t/cmdlinecalc-divzero.txtar
+++ b/t/cmdlinecalc-divzero.txtar
@@ -1,2 +1,2 @@
-exec testrpn 100 50 50 - /
-stdout 'division by null\n'
+! exec testrpn 100 50 50 - /
+stdout 'division by null'