diff --git a/src/executorlib/standalone/select.py b/src/executorlib/standalone/select.py
index f0edc082..37a6cbbf 100644
--- a/src/executorlib/standalone/select.py
+++ b/src/executorlib/standalone/select.py
@@ -20,7 +20,20 @@ def __setattr__(self, name: str, value: Any):
     def result(self, timeout: Optional[float] = None) -> Any:
         result = self._future.result(timeout=timeout)
         if result is not None:
-            return result[self._selector]
+            if (
+                isinstance(self._selector, int) and isinstance(result, (tuple, list))
+            ) or self._selector in result:
+                return result[self._selector]
+            else:
+                raise KeyError(
+                    str(self._selector)
+                    + " of type "
+                    + str(type(self._selector))
+                    + " is not in "
+                    + str(result)
+                    + " of type "
+                    + str(type(result))
+                )
         else:
             return None