diff --git a/BlenderMalt/MaltNodes/Nodes/MaltIONode.py b/BlenderMalt/MaltNodes/Nodes/MaltIONode.py
index 77f9bd3f..0bb1c270 100644
--- a/BlenderMalt/MaltNodes/Nodes/MaltIONode.py
+++ b/BlenderMalt/MaltNodes/Nodes/MaltIONode.py
@@ -141,8 +141,7 @@ def get_source_global_parameters(self, transpiler):
         src = MaltNode.get_source_global_parameters(self, transpiler)
         custom_outputs = ''
         graph_io = self.id_data.get_pipeline_graph().graph_io[self.io_type]
-        try: index = graph_io.custom_output_start_index
-        except: index = 0
+        index = graph_io.custom_output_start_index
         for key, parameter in self.get_custom_parameters().items():
             if parameter.is_output:
                 socket = self.inputs[key]
@@ -197,7 +196,13 @@ def add_custom_socket():
                     while f'{name} {i}' in parameters.keys():
                         i += 1
                     new_param.name = f'{name} {i}'
-                col.operator("wm.malt_callback", text='', icon='ADD').callback.set(add_custom_socket, 'Add')
+                add_row = col.row()
+                graph = self.id_data.get_pipeline_graph()
+                if (self.is_output and graph.language == 'GLSL' and
+                len(parameters) >= (8 - graph.graph_io[self.io_type].custom_output_start_index) and
+                self.id_data.graph_type.endswith("(Group)") == False): 
+                    add_row.enabled = False
+                add_row.operator("wm.malt_callback", text='', icon='ADD').callback.set(add_custom_socket, 'Add')
                 def remove_custom_socket():
                     parameters.remove(index)
                 col.operator("wm.malt_callback", text='', icon='REMOVE').callback.set(remove_custom_socket, 'Remove')
diff --git a/Malt/PipelineGraph.py b/Malt/PipelineGraph.py
index 246cc06b..39518289 100644
--- a/Malt/PipelineGraph.py
+++ b/Malt/PipelineGraph.py
@@ -11,6 +11,7 @@ def __init__(self, name, dynamic_input_types = [], dynamic_output_types = [],
         self.default_dynamic_inputs = default_dynamic_inputs
         self.default_dynamic_outputs = default_dynamic_outputs
         self.function = function
+        self.custom_output_start_index = 0
 
 class PipelineGraph():