diff --git a/config/mutations.go b/config/mutations.go
index ae26b43..d75346e 100644
--- a/config/mutations.go
+++ b/config/mutations.go
@@ -374,11 +374,12 @@ func InterfaceToType(ts *guts.Typescript) {
 
 		// Replace the interface with a type alias
 		ts.ReplaceNode(key, &bindings.Alias{
-			Name:       intf.Name,
-			Modifiers:  intf.Modifiers,
-			Type:       typeLiteral,
-			Parameters: intf.Parameters,
-			Source:     intf.Source,
+			Name:            intf.Name,
+			Modifiers:       intf.Modifiers,
+			Type:            typeLiteral,
+			Parameters:      intf.Parameters,
+			Source:          intf.Source,
+			SupportComments: intf.SupportComments,
 		})
 	})
 }
diff --git a/testdata/interfacetotype-comments/interfacetotype-comments.go b/testdata/interfacetotype-comments/interfacetotype-comments.go
new file mode 100644
index 0000000..9f568d8
--- /dev/null
+++ b/testdata/interfacetotype-comments/interfacetotype-comments.go
@@ -0,0 +1,29 @@
+package codersdk
+
+// User represents a user in the system.
+// This comment should be preserved after conversion to a type alias.
+type User struct {
+	// ID is the unique identifier
+	ID string `json:"id"`
+	// Name is the user's full name
+	Name string `json:"name"`
+	// Email is the user's email address
+	Email string `json:"email"`
+}
+
+// Address contains location information.
+type Address struct {
+	// Street address
+	Street string `json:"street"`
+	// City name
+	City string `json:"city"`
+}
+
+// Profile combines user and address information.
+// It extends multiple types.
+type Profile struct {
+	User
+	Address
+	// Bio is the user's biography
+	Bio string `json:"bio"`
+}
diff --git a/testdata/interfacetotype-comments/interfacetotype-comments.ts b/testdata/interfacetotype-comments/interfacetotype-comments.ts
new file mode 100644
index 0000000..91127e4
--- /dev/null
+++ b/testdata/interfacetotype-comments/interfacetotype-comments.ts
@@ -0,0 +1,48 @@
+// Code generated by 'guts'. DO NOT EDIT.
+
+// From codersdk/interfacetotype-comments.go
+/**
+ * Address contains location information.
+ */
+export type Address = {
+    /**
+     * Street address
+     */
+    street: string;
+    /**
+     * City name
+     */
+    city: string;
+};
+
+// From codersdk/interfacetotype-comments.go
+/**
+ * Profile combines user and address information.
+ * It extends multiple types.
+ */
+export type Profile = User & Address & {
+    /**
+     * Bio is the user's biography
+     */
+    bio: string;
+};
+
+// From codersdk/interfacetotype-comments.go
+/**
+ * User represents a user in the system.
+ * This comment should be preserved after conversion to a type alias.
+ */
+export type User = {
+    /**
+     * ID is the unique identifier
+     */
+    id: string;
+    /**
+     * Name is the user's full name
+     */
+    name: string;
+    /**
+     * Email is the user's email address
+     */
+    email: string;
+};
diff --git a/testdata/interfacetotype-comments/mutations b/testdata/interfacetotype-comments/mutations
new file mode 100644
index 0000000..92ae551
--- /dev/null
+++ b/testdata/interfacetotype-comments/mutations
@@ -0,0 +1 @@
+InterfaceToType,ExportTypes,ReadOnly
\ No newline at end of file