diff --git a/strax/context.py b/strax/context.py
index e0c0e3a3..f9b87f03 100644
--- a/strax/context.py
+++ b/strax/context.py
@@ -578,7 +578,8 @@ def register_all(self, module):
             if not isinstance(x, type(type)):
                 continue
             if issubclass(x, strax.Plugin):
-                self.register(x)
+                if x.__module__ == module.__name__:  # Ensure it's defined in the given module
+                    self.register(x)
 
     def register_cut_list(self, cut_list):
         """Register cut lists to strax context.