diff --git a/hugr-core/src/extension.rs b/hugr-core/src/extension.rs
index 22e1bb3b4..e1674afac 100644
--- a/hugr-core/src/extension.rs
+++ b/hugr-core/src/extension.rs
@@ -52,8 +52,9 @@ pub struct ExtensionRegistry {
     /// A flag indicating whether the current set of extensions has been
     /// validated.
     ///
-    /// This is used to avoid re-validating the extensions every time they are
-    /// used, and is set to `false` whenever a new extension is added.
+    /// This is used to avoid re-validating the extensions every time the
+    /// registry is validated, and is set to `false` whenever a new extension is
+    /// added.
     valid: AtomicBool,
 }
 
diff --git a/hugr-core/src/extension/resolution.rs b/hugr-core/src/extension/resolution.rs
index db2ad12ff..3ccaeb857 100644
--- a/hugr-core/src/extension/resolution.rs
+++ b/hugr-core/src/extension/resolution.rs
@@ -23,7 +23,7 @@ mod ops;
 mod types;
 mod types_mut;
 
-pub(crate) use ops::{collect_op_extensions, resolve_op_extensions};
+pub(crate) use ops::{collect_op_extension, resolve_op_extensions};
 pub(crate) use types::{collect_op_types_extensions, collect_signature_exts};
 pub(crate) use types_mut::resolve_op_types_extensions;
 
diff --git a/hugr-core/src/extension/resolution/ops.rs b/hugr-core/src/extension/resolution/ops.rs
index 76b290434..42e3954dd 100644
--- a/hugr-core/src/extension/resolution/ops.rs
+++ b/hugr-core/src/extension/resolution/ops.rs
@@ -20,12 +20,12 @@ use crate::Node;
 /// invalidated if the original `Arc<Extension>` is dropped. On such cases, we
 /// return an error with the missing extension names.
 ///
-/// # Attributes
+/// # Parameters
 ///
 /// - `node`: The node where the operation is located, if available. This is
 ///   used to provide context in the error message.
 /// - `op`: The operation to collect the extensions from.
-pub(crate) fn collect_op_extensions(
+pub(crate) fn collect_op_extension(
     node: Option<Node>,
     op: &OpType,
 ) -> Result<Option<Arc<Extension>>, ExtensionCollectionError> {
diff --git a/hugr-core/src/extension/resolution/types_mut.rs b/hugr-core/src/extension/resolution/types_mut.rs
index 554b73472..7f8f16f4c 100644
--- a/hugr-core/src/extension/resolution/types_mut.rs
+++ b/hugr-core/src/extension/resolution/types_mut.rs
@@ -13,12 +13,12 @@ use crate::types::type_row::TypeRowBase;
 use crate::types::{MaybeRV, Signature, SumType, TypeArg, TypeBase, TypeEnum};
 use crate::Node;
 
-/// Replace the dangling extension pointer in the [`CustomType`]s inside a
-/// signature with a valid pointer to the extension in the `extensions`
+/// Replace the dangling extension pointer in the [`CustomType`]s inside an
+/// optype with a valid pointer to the extension in the `extensions`
 /// registry.
 ///
 /// When a pointer is replaced, the extension is added to the
-/// `used_extensions` registry and the new type definition is returned.
+/// `used_extensions` registry.
 ///
 /// This is a helper function used right after deserializing a Hugr.
 pub fn resolve_op_types_extensions(
diff --git a/hugr-core/src/ops.rs b/hugr-core/src/ops.rs
index 7815d7ea1..05f854589 100644
--- a/hugr-core/src/ops.rs
+++ b/hugr-core/src/ops.rs
@@ -10,7 +10,7 @@ pub mod sum;
 pub mod tag;
 pub mod validate;
 use crate::extension::resolution::{
-    collect_op_extensions, collect_op_types_extensions, ExtensionCollectionError,
+    collect_op_extension, collect_op_types_extensions, ExtensionCollectionError,
 };
 use crate::extension::simple_op::MakeExtensionOp;
 use crate::extension::{ExtensionId, ExtensionRegistry, ExtensionSet};
@@ -313,7 +313,7 @@ impl OpType {
         }
     }
 
-    /// Returns a register with all the extensions required by the operation.
+    /// Returns a registry with all the extensions required by the operation.
     ///
     /// This includes the operation extension in [`OpType::extension_id`], and any
     /// extension required by the operation's signature types.
@@ -321,7 +321,7 @@ impl OpType {
         // Collect extensions on the types.
         let mut reg = collect_op_types_extensions(None, self)?;
         // And on the operation definition itself.
-        if let Some(ext) = collect_op_extensions(None, self)? {
+        if let Some(ext) = collect_op_extension(None, self)? {
             reg.register_updated(ext);
         }
         Ok(reg)