diff --git a/src/builder/build_traits.rs b/src/builder/build_traits.rs
index 22c7267af..d76b5727b 100644
--- a/src/builder/build_traits.rs
+++ b/src/builder/build_traits.rs
@@ -292,10 +292,7 @@ pub trait Dataflow: Container {
         let op = ops::DFG {
             signature: signature.clone(),
         };
-        let nodetype = match &input_extensions {
-            None => NodeType::open_extensions(op),
-            Some(rs) => NodeType::new(op, rs.clone()),
-        };
+        let nodetype = NodeType::new(op, input_extensions.clone());
         let (dfg_n, _) = add_node_with_wires(self, nodetype, input_wires.into_iter().collect())?;
 
         DFGBuilder::create_with_io(self.hugr_mut(), dfg_n, signature, input_extensions)
diff --git a/src/builder/dataflow.rs b/src/builder/dataflow.rs
index 89ac001ac..07c1e2f97 100644
--- a/src/builder/dataflow.rs
+++ b/src/builder/dataflow.rs
@@ -49,20 +49,14 @@ impl<T: AsMut<Hugr> + AsRef<Hugr>> DFGBuilder<T> {
         let output = ops::Output {
             types: signature.output().clone(),
         };
+        base.as_mut()
+            .add_node_with_parent(parent, NodeType::new(input, input_extensions.clone()))?;
         base.as_mut().add_node_with_parent(
             parent,
-            match &input_extensions {
-                None => NodeType::open_extensions(input),
-                Some(rs) => NodeType::new(input, rs.clone()),
-            },
-        )?;
-        base.as_mut().add_node_with_parent(
-            parent,
-            match input_extensions.map(|inp| inp.union(&signature.extension_reqs)) {
-                // TODO: Make this NodeType::open_extensions
-                None => NodeType::open_extensions(output),
-                Some(rs) => NodeType::new(output, rs),
-            },
+            NodeType::new(
+                output,
+                input_extensions.map(|inp| inp.union(&signature.extension_reqs)),
+            ),
         )?;
 
         Ok(Self {
diff --git a/src/hugr.rs b/src/hugr.rs
index 8e5a30c45..f697c63b7 100644
--- a/src/hugr.rs
+++ b/src/hugr.rs
@@ -66,10 +66,10 @@ pub struct NodeType {
 
 impl NodeType {
     /// Create a new optype with some ExtensionSet
-    pub fn new(op: impl Into<OpType>, input_extensions: ExtensionSet) -> Self {
+    pub fn new(op: impl Into<OpType>, input_extensions: impl Into<Option<ExtensionSet>>) -> Self {
         NodeType {
             op: op.into(),
-            input_extensions: Some(input_extensions),
+            input_extensions: input_extensions.into(),
         }
     }
 
diff --git a/src/hugr/serialize.rs b/src/hugr/serialize.rs
index 953253e8e..5870da98c 100644
--- a/src/hugr/serialize.rs
+++ b/src/hugr/serialize.rs
@@ -210,10 +210,7 @@ impl TryFrom<SerHugrV0> for Hugr {
         // if there are any unconnected ports or copy nodes the capacity will be
         // an underestimate
         let mut hugr = Hugr::with_capacity(
-            match input_extensions {
-                None => NodeType::open_extensions(root_type),
-                Some(rs) => NodeType::new(root_type, rs),
-            },
+            NodeType::new(root_type, input_extensions),
             nodes.len(),
             edges.len() * 2,
         );
diff --git a/src/ops/custom.rs b/src/ops/custom.rs
index 85dacb559..c5262ee43 100644
--- a/src/ops/custom.rs
+++ b/src/ops/custom.rs
@@ -252,10 +252,7 @@ pub fn resolve_extension_ops(
     // Only now can we perform the replacements as the 'for' loop was borrowing 'h' preventing use from using it mutably
     for (n, op) in replacements {
         let leaf: LeafOp = op.into();
-        let node_type = match h.get_nodetype(n).input_extensions() {
-            None => NodeType::open_extensions(leaf),
-            Some(exts) => NodeType::new(leaf, exts.clone()),
-        };
+        let node_type = NodeType::new(leaf, h.get_nodetype(n).input_extensions().cloned());
         h.replace_op(n, node_type);
     }
     Ok(())