diff --git a/robot/cli_core.robot b/robot/cli_core.robot
index e9a158e66..54db72b23 100644
--- a/robot/cli_core.robot
+++ b/robot/cli_core.robot
@@ -102,9 +102,9 @@ Diagnostics Command Plain Format
     Should Contain    ${result.stdout}    summary:
 
 Diagnostics Command Check Flag Returns Valid Exit Code
-    [Documentation]    Diagnostics --check exits 0 (no errors) or 1 (has errors) without crashing
+    [Documentation]    Diagnostics --check exits 0 when no errors are found
     ${result}=    Run Process    ${PYTHON}    -m    cleveragents    diagnostics    --check    --format    json    timeout=60s
-    Should Be True    ${result.rc} == 0 or ${result.rc} == 1    Unexpected exit code: ${result.rc}
+    Should Be Equal As Integers    ${result.rc}    0    Diagnostics --check failed with rc=${result.rc}: ${result.stdout}
     Should Contain    ${result.stdout}    "checks"
     Should Contain    ${result.stdout}    "has_errors"