diff --git a/src/transformers/modeling_utils.py b/src/transformers/modeling_utils.py
index 1cdb033cb709..59bee80e7a89 100644
--- a/src/transformers/modeling_utils.py
+++ b/src/transformers/modeling_utils.py
@@ -1948,9 +1948,9 @@ def _can_set_attn_implementation(cls) -> bool:
         """Detect whether the class supports setting its attention implementation dynamically. It is an ugly check based on
         opening the file, but avoids maintaining yet another property flag.
         """
-        class_module = sys.modules[cls.__module__]
+        class_module = sys.modules.get(cls.__module__)
         # This can happen for a custom model in a jupyter notebook or repl for example - simply do not allow to set it then
-        if not hasattr(class_module, "__file__"):
+        if class_module is None or not hasattr(class_module, "__file__"):
             return False
         class_file = class_module.__file__
         with open(class_file, "r", encoding="utf-8") as f:
@@ -1967,9 +1967,9 @@ def _can_set_experts_implementation(cls) -> bool:
         """Detect whether the class supports setting its experts implementation dynamically. It is an ugly check based on
         opening the file, but avoids maintaining yet another property flag.
         """
-        class_module = sys.modules[cls.__module__]
+        class_module = sys.modules.get(cls.__module__)
         # This can happen for a custom model in a jupyter notebook or repl for example - simply do not allow to set it then
-        if not hasattr(class_module, "__file__"):
+        if class_module is None or not hasattr(class_module, "__file__"):
             return False
         class_file = class_module.__file__
         with open(class_file, "r", encoding="utf-8") as f: