diff --git a/src/renderer_mtl.mm b/src/renderer_mtl.mm
index c9c6b42fdd..0a7d909e98 100644
--- a/src/renderer_mtl.mm
+++ b/src/renderer_mtl.mm
@@ -2049,7 +2049,7 @@ void processArguments(
 								}
 								else
 								{
-									ps->m_bindingTypes[arg.index-1] = fragmentBit
+									ps->m_bindingTypes[arg.index-1] |= fragmentBit
 										? PipelineStateMtl::BindToFragmentShader
 										: PipelineStateMtl::BindToVertexShader
 										;
@@ -2067,7 +2067,7 @@ void processArguments(
 							}
 							else
 							{
-								ps->m_bindingTypes[arg.index] = fragmentBit
+								ps->m_bindingTypes[arg.index] |= fragmentBit
 									? PipelineStateMtl::BindToFragmentShader
 									: PipelineStateMtl::BindToVertexShader
 									;