diff --git a/hecl/extern/boo b/hecl/extern/boo
index ca20aea83..73891af56 160000
--- a/hecl/extern/boo
+++ b/hecl/extern/boo
@@ -1 +1 @@
-Subproject commit ca20aea8344d8bef8d85047e253e97fa27563f1f
+Subproject commit 73891af56a633cf2b4e047b6422f34c80230eb29
diff --git a/hecl/lib/Backend/Metal.cpp b/hecl/lib/Backend/Metal.cpp
index b4f7ba4c8..a6300aa3d 100644
--- a/hecl/lib/Backend/Metal.cpp
+++ b/hecl/lib/Backend/Metal.cpp
@@ -408,7 +408,7 @@ struct MetalBackendFactory : IShaderBackendFactory
                               boo::BlendFactor(m_backend.m_blendDst),
                               tag.getPrimType(),
                               tag.getDepthTest(), tag.getDepthWrite(),
-                              tag.getBackfaceCulling());
+                              tag.getBackfaceCulling() ? boo::CullMode::Backface : boo::CullMode::None);
         if (!objOut)
             Log.report(logvisor::Fatal, "unable to build shader");
 
@@ -445,7 +445,7 @@ struct MetalBackendFactory : IShaderBackendFactory
                               tag.newVertexFormat(ctx), m_rtHint,
                               blendSrc, blendDst, tag.getPrimType(),
                               tag.getDepthTest(), tag.getDepthWrite(),
-                              tag.getBackfaceCulling());
+                              tag.getBackfaceCulling() ? boo::CullMode::Backface : boo::CullMode::None);
         if (!ret)
             Log.report(logvisor::Fatal, "unable to build shader");
         return ret;
@@ -484,7 +484,7 @@ struct MetalBackendFactory : IShaderBackendFactory
                                   boo::BlendFactor((slot.dstFactor == hecl::Backend::BlendFactor::Original) ? m_backend.m_blendDst : slot.dstFactor),
                                   tag.getPrimType(),
                                   tag.getDepthTest(), tag.getDepthWrite(),
-                                  tag.getBackfaceCulling());
+                                  tag.getBackfaceCulling() ? boo::CullMode::Backface : boo::CullMode::None);
             if (!ret)
                 Log.report(logvisor::Fatal, "unable to build shader");
             returnFunc(ret);
@@ -536,7 +536,7 @@ struct MetalBackendFactory : IShaderBackendFactory
                                   boo::BlendFactor((slot.dstFactor == hecl::Backend::BlendFactor::Original) ? blendDst : slot.dstFactor),
                                   tag.getPrimType(),
                                   tag.getDepthTest(), tag.getDepthWrite(),
-                                  tag.getBackfaceCulling());
+                                  tag.getBackfaceCulling() ? boo::CullMode::Backface : boo::CullMode::None);
             if (!ret)
                 Log.report(logvisor::Fatal, "unable to build shader");
             returnFunc(ret);