diff --git a/materialx/bl_nodes/shader.py b/materialx/bl_nodes/shader.py
index 219d32135..6ab39ce68 100644
--- a/materialx/bl_nodes/shader.py
+++ b/materialx/bl_nodes/shader.py
@@ -5,6 +5,7 @@ import math
 import MaterialX as mx
 
 from .node_parser import NodeParser
+from ..utils import get_mx_node_input_types
 from . import log
 
 
@@ -227,18 +228,31 @@ class ShaderNodeMixShader(NodeParser):
         shader2 = self.get_input_link(2)
 
         mix = None
+        input_types = get_mx_node_input_types('mix', 'PBR')
 
         if shader1 is None and shader2 is None:
             return None
 
         if shader2 is None:
-            mix = self.create_node('mix', get_node_type(shader1).lower(), prefix='PBR', inputs={
+            shader1_type = get_node_type(shader1)
+            if shader1_type not in input_types:
+                log.warn(f'Node {self.node.bl_idname} ({self.material.name_full}) ignored. '
+                         f'Input type must be of types {input_types}, actual: {shader1_type}')
+                return shader1
+
+            mix = self.create_node('mix', shader1_type.lower(), prefix='PBR', inputs={
                 'fg': shader1,
                 'mix': factor
             })
 
         if shader1 is None:
-            mix = self.create_node('mix', get_node_type(shader2).lower(), prefix='PBR', inputs={
+            shader2_type = get_node_type(shader2)
+            if shader2_type not in input_types:
+                log.warn(f'Node {self.node.bl_idname} ({self.material.name_full}) ignored. '
+                         f'Input type must be of types {input_types}, actual: {shader2_type}')
+                return shader2
+
+            mix = self.create_node('mix', shader2_type.lower(), prefix='PBR', inputs={
                 'bg': shader2,
                 'mix': factor
             })
@@ -247,10 +261,15 @@ class ShaderNodeMixShader(NodeParser):
             shader1_type = get_node_type(shader1)
             shader2_type = get_node_type(shader2)
             if shader1_type != shader2_type:
-                log.warn(f'Types of input shaders must be the same.'
-                         f' First shader type: {shader1_type}, second shader type: {shader2_type}')
+                log.warn(f'Types of input shaders must be the same. '
+                         f'First shader type: {shader1_type}, second shader type: {shader2_type}')
 
-                return None
+                return shader1
+
+            if shader1_type not in input_types:
+                log.warn(f'Node {self.node.bl_idname} ({self.material.name_full}) ignored. '
+                         f'Input type must be of types {input_types}, actual: {shader1_type}, {shader2_type}')
+                return shader1
 
             mix = self.create_node('mix', shader1_type.lower(), prefix='PBR', inputs={
                 'fg': shader1,
@@ -277,17 +296,30 @@ class ShaderNodeAddShader(NodeParser):
         shader2 = self.get_input_link(1)
 
         add = None
+        input_types = get_mx_node_input_types('add', 'PBR')
 
         if shader1 is None and shader2 is None:
             return None
 
         if shader2 is None:
-            add = self.create_node('add', get_node_type(shader1).lower(), prefix='PBR', inputs={
+            shader1_type = get_node_type(shader1)
+            if shader1_type not in input_types:
+                log.warn(f'Node {self.node.bl_idname} ({self.material.name_full}) ignored. '
+                         f'Input type must be of types {input_types}, actual: {shader1_type}')
+                return shader1
+
+            add = self.create_node('add', shader1_type.lower(), prefix='PBR', inputs={
                 'in1': shader1
             })
 
         if shader1 is None:
-            add = self.create_node('add', get_node_type(shader2).lower(), prefix='PBR', inputs={
+            shader2_type = get_node_type(shader2)
+            if shader2_type not in input_types:
+                log.warn(f'Node {self.node.bl_idname} ({self.material.name_full}) ignored. '
+                         f'Input type must be of types {input_types}, actual: {shader2_type}')
+                return shader2
+
+            add = self.create_node('add', shader2_type.lower(), prefix='PBR', inputs={
                 'in2': shader2
             })
 
@@ -295,10 +327,15 @@ class ShaderNodeAddShader(NodeParser):
             shader1_type = get_node_type(shader1)
             shader2_type = get_node_type(shader2)
             if shader1_type != shader2_type:
-                log.warn(f'Types of input shaders must be the same.'
-                         f' First shader type: {shader1_type}, second shader type: {shader2_type}')
+                log.warn(f'Types of input shaders must be the same. '
+                         f'First shader type: {shader1_type}, second shader type: {shader2_type}')
 
-                return None
+                return shader1
+
+            if shader1_type not in input_types:
+                log.warn(f'Node {self.node.bl_idname} ({self.material.name_full}) ignored. '
+                         f'Input type must be of types {input_types}, actual: {shader1_type}, {shader2_type}')
+                return shader1
 
             add = self.create_node('add', shader1_type.lower(), prefix='PBR', inputs={
                 'in1': shader1,
diff --git a/materialx/utils.py b/materialx/utils.py
index fbb1bb21d..6964386a4 100644
--- a/materialx/utils.py
+++ b/materialx/utils.py
@@ -662,3 +662,19 @@ def get_output_node(material):
                  node.inputs['surfaceshader'].links), None)
 
     return mx_output_node
+
+
+def get_mx_node_input_types(node_name, prefix=''):
+    from .nodes import mx_node_classes
+
+    suffix = f'_{node_name}'
+    if prefix:
+        suffix = prefix + suffix
+
+    input_types = set()
+    classes = tuple(cls for cls in mx_node_classes if cls.__name__.endswith(suffix))
+    for cls in classes:
+        for nodedef, data_type in cls.get_nodedefs():
+            input_types |= {p.getType() for p in nodedef.getActiveInputs()}
+
+    return input_types