diff --git a/Sources/OpenSwiftUI/Core/Graph/GraphHost.swift b/Sources/OpenSwiftUI/Core/Graph/GraphHost.swift
index a156b7ca..c7575b33 100644
--- a/Sources/OpenSwiftUI/Core/Graph/GraphHost.swift
+++ b/Sources/OpenSwiftUI/Core/Graph/GraphHost.swift
@@ -39,7 +39,7 @@ class GraphHost {
             // data.globalSubgraph.apply
             isInstantiated = false
         }
-        if let graph = data.graph {
+        if let _ = data.graph {
             data.globalSubgraph.invalidate()
             // graph.context = nil
             // graph.invalidate()
diff --git a/Sources/OpenSwiftUI/Core/Graph/GraphMutation.swift b/Sources/OpenSwiftUI/Core/Graph/GraphMutation.swift
index a23b4566..7b9f6a80 100644
--- a/Sources/OpenSwiftUI/Core/Graph/GraphMutation.swift
+++ b/Sources/OpenSwiftUI/Core/Graph/GraphMutation.swift
@@ -19,6 +19,8 @@ struct EmptyGraphMutation: GraphMutation {
     }
 }
 
+// FIXME: #39
+#if canImport(Darwin)
 struct InvalidatingGraphMutation: GraphMutation {
     let attribute: OGWeakAttribute
     
@@ -33,6 +35,7 @@ struct InvalidatingGraphMutation: GraphMutation {
         return mutation.attribute == attribute
     }
 }
+#endif
 
 struct CustomGraphMutation: GraphMutation {
     let body: () -> Void