diff --git a/plugins/3MFReader/__init__.py b/plugins/3MFReader/__init__.py
index 3c2228e055..6e3e5aa918 100644
--- a/plugins/3MFReader/__init__.py
+++ b/plugins/3MFReader/__init__.py
@@ -31,7 +31,7 @@ def getMetaData() -> Dict:
             "api": 3
         }
     }
-    if "ThreeMFReader" in sys.modules:
+    if "3MFReader.ThreeMFReader" in sys.modules:
         metaData["mesh_reader"] = [
             {
                 "extension": "3mf",
@@ -49,7 +49,7 @@ def getMetaData() -> Dict:
 
 
 def register(app):
-    if "ThreeMFReader" in sys.modules:
+    if "3MFReader.ThreeMFReader" in sys.modules:
         return {"mesh_reader": ThreeMFReader.ThreeMFReader(),
                 "workspace_reader": ThreeMFWorkspaceReader.ThreeMFWorkspaceReader()}
     else:
diff --git a/plugins/3MFWriter/__init__.py b/plugins/3MFWriter/__init__.py
index 7cd79d2e1f..09bf06749e 100644
--- a/plugins/3MFWriter/__init__.py
+++ b/plugins/3MFWriter/__init__.py
@@ -24,7 +24,7 @@ def getMetaData():
         }
     }
 
-    if "ThreeMFWriter" in sys.modules:
+    if "3MFWriter.ThreeMFWriter" in sys.modules:
         metaData["mesh_writer"] = {
             "output": [{
                 "extension": "3mf",
@@ -45,7 +45,7 @@ def getMetaData():
     return metaData
 
 def register(app):
-    if "ThreeMFWriter" in sys.modules:
+    if "3MFWriter.ThreeMFWriter" in sys.modules:
         return {"mesh_writer": ThreeMFWriter.ThreeMFWriter(), 
                 "workspace_writer": ThreeMFWorkspaceWriter.ThreeMFWorkspaceWriter()}
     else: