diff --git a/.codesandbox/ci.json b/.codesandbox/ci.json
new file mode 100644
index 000000000..46f8c9048
--- /dev/null
+++ b/.codesandbox/ci.json
@@ -0,0 +1,3 @@
+{
+  "buildCommand": "small-build"
+}
\ No newline at end of file
diff --git a/src/api/action.ts b/src/api/action.ts
index 2fdbb5b73..6438ba9e8 100644
--- a/src/api/action.ts
+++ b/src/api/action.ts
@@ -86,7 +86,7 @@ export function runInAction(arg1, arg2?) {
             "`runInAction` expects a function without arguments"
         )
         if (typeof actionName !== "string" || !actionName)
-            fail(`actions should have valid names, got: '${actionName}'`)
+            fail(`actions should have a valid name, got: '${actionName}'`)
     }
 
     return executeAction(actionName, fn, this, undefined)