diff --git a/xls/dslx/fmt/BUILD b/xls/dslx/fmt/BUILD
index d7215c8545..5ed8a6133b 100644
--- a/xls/dslx/fmt/BUILD
+++ b/xls/dslx/fmt/BUILD
@@ -166,6 +166,7 @@ cc_library(
         "//xls/dslx/frontend:comment_data",
         "//xls/dslx/frontend:module",
         "//xls/dslx/frontend:pos",
+        "@com_google_absl//absl/container:flat_hash_set",
         "@com_google_absl//absl/log",
         "@com_google_absl//absl/status",
         "@com_google_absl//absl/status:statusor",
diff --git a/xls/dslx/fmt/ast_fmt.cc b/xls/dslx/fmt/ast_fmt.cc
index 1eebb49fb6..059bdbe3c4 100644
--- a/xls/dslx/fmt/ast_fmt.cc
+++ b/xls/dslx/fmt/ast_fmt.cc
@@ -2414,6 +2414,7 @@ DocRef Formatter::Format(const ImplMember& n) {
   return absl::visit(Visitor{
                          [&](const Function* n) { return Format(*n); },
                          [&](const ConstantDef* n) { return Format(*n); },
+                         [&](const VerbatimNode* n) { return Format(*n); },
                      },
                      n);
 }
diff --git a/xls/dslx/fmt/ast_fmt_test.cc b/xls/dslx/fmt/ast_fmt_test.cc
index 62ac8de30e..dd18731342 100644
--- a/xls/dslx/fmt/ast_fmt_test.cc
+++ b/xls/dslx/fmt/ast_fmt_test.cc
@@ -1603,6 +1603,54 @@ impl MyStruct {
 )");
 }
 
+TEST_F(ModuleFmtTest, ImplWithDisabledFmtFn) {
+  DoFmt(
+      R"(struct MyStruct {}
+
+impl MyStruct {
+    // dslx-fmt::off
+fn my_function() -> u32 {
+// Do something important.
+u32:3
+}
+// dslx-fmt::on
+
+}
+)");
+}
+
+TEST_F(ModuleFmtTest, ImplWithDisabledFmtExpr) {
+  DoFmt(
+      R"(struct MyStruct {}
+
+impl MyStruct {
+    fn my_function() -> u32 {
+        // dslx-fmt::off
+// Do something important.
+u32:3
+// dslx-fmt::on
+
+    }
+}
+)");
+}
+
+TEST_F(ModuleFmtTest, DISABLED_ImplWithDisabledFmtImpl) {
+  // This test is disabled because the impl becomes a VerbatimNode. Then the
+  // cloner tries to set it into the struct as its impl, but structs cannot
+  // take VerbatimNodes as their impl yet.
+  DoFmt(
+      R"(struct MyStruct {}
+
+// dslx-fmt::off
+impl MyStruct { fn my_function() -> u32 {
+// Do something important.
+u32:3
+}}
+// dslx-fmt::on
+)");
+}
+
 TEST_F(ModuleFmtTest, ImplMethodWithVars) {
   DoFmt(R"(struct MyStruct { x: u32 }
 
diff --git a/xls/dslx/fmt/format_disabler.cc b/xls/dslx/fmt/format_disabler.cc
index b9d2c35b0c..879cdfd3f5 100644
--- a/xls/dslx/fmt/format_disabler.cc
+++ b/xls/dslx/fmt/format_disabler.cc
@@ -55,33 +55,44 @@ bool IsInDesugaredFn(const AstNode *node) {
 
 absl::StatusOr<std::optional<AstNode *>> FormatDisabler::operator()(
     const AstNode *node) {
+  if (seen_nodes_.contains(node)) {
+    return std::nullopt;
+  }
+  seen_nodes_.insert(node);
+
   if (node == nullptr || !node->GetSpan().has_value()) {
     // If there's no node, or no span, we can't know if it's in the unformatted
     // range, so just return nullopt to indicate it should be unchanged.
     return std::nullopt;
   }
+  VLOG(5) << "FormatDisabler looking at " << node->ToString() << " @ "
+          << (*node->GetSpan()).ToString(node->owner()->file_name());
 
   // If this node is part of a desugared proc function, we skip it, because it
   // won't be formatted anyway.
   // TODO: https://github.com/google/xls/issues/1029 remove desugared proc
   // functions.
   if (IsInDesugaredFn(node)) {
+    VLOG(5) << "In desugared function, stopping";
     return std::nullopt;
   }
 
   if (unformatted_end_.has_value()) {
+    VLOG(6) << "In format disabled mode";
     // We are in "format disabled" mode.
 
     if (node->GetSpan()->start() < *unformatted_end_) {
       // This node is within the unformatted range; delete it by returning
       // an empty VerbatimNode. This is safe because its text has already been
       // extracted in a VerbatimNode.
+      VLOG(5) << "Setting previous node to " << node->ToString();
       previous_node_ = node;
 
       return node->owner()->Make<VerbatimNode>(*node->GetSpan());
     }
 
     // We're past the end of the unformatted range; clear the setting.
+    VLOG(5) << "Past end of unformatted range";
     unformatted_end_ = std::nullopt;
 
     // Note: continue and process this node normally now.
@@ -91,6 +102,8 @@ absl::StatusOr<std::optional<AstNode *>> FormatDisabler::operator()(
   std::vector<const CommentData *> disable_comments =
       FindDisablesBetween(previous_node_, node);
   if (disable_comments.empty()) {
+    VLOG(5) << "No comments between previous node and this node";
+    VLOG(5) << "Setting previous node to " << node->ToString();
     previous_node_ = node;
     // Node should be unchanged.
     return std::nullopt;
@@ -105,6 +118,7 @@ absl::StatusOr<std::optional<AstNode *>> FormatDisabler::operator()(
         absl::StrCat("Multiple dslx-fmt::off commands between ",
                      previous_node_->ToString(), " and ", node->ToString()));
   }
+  VLOG(5) << "Found disable comment between previous node and this node.";
   const CommentData *disable_comment = disable_comments[0];
 
   // If there's a disable comment between the previous node and this node:
@@ -134,11 +148,14 @@ absl::StatusOr<std::optional<AstNode *>> FormatDisabler::operator()(
 
   // d. Set a field that indicates the ending position of the last node that
   // should be unformatted.
+  VLOG(6) << "Setting unformatted end to " << limit;
   unformatted_end_ = limit;
 
   previous_node_ = node;
 
   // e. Replace the current node with the verbatim node from step c
+  VLOG(5) << "Setting previous node to, and replacing " << node->ToString()
+          << " with VerbatimNode";
   return verbatim_node;
 }
 
diff --git a/xls/dslx/fmt/format_disabler.h b/xls/dslx/fmt/format_disabler.h
index 900f8433b1..a1f90a7bf1 100644
--- a/xls/dslx/fmt/format_disabler.h
+++ b/xls/dslx/fmt/format_disabler.h
@@ -21,6 +21,7 @@
 #include <string_view>
 #include <vector>
 
+#include "absl/container/flat_hash_set.h"
 #include "absl/status/status.h"
 #include "absl/status/statusor.h"
 #include "xls/dslx/fmt/comments.h"
@@ -87,6 +88,7 @@ class FormatDisabler {
 
   // Parsed lines of the module.
   std::vector<std::string> lines_;
+  absl::flat_hash_set<const AstNode *> seen_nodes_;
 };
 
 }  // namespace xls::dslx
diff --git a/xls/dslx/frontend/ast.cc b/xls/dslx/frontend/ast.cc
index 2a9c715b9a..06184091a6 100644
--- a/xls/dslx/frontend/ast.cc
+++ b/xls/dslx/frontend/ast.cc
@@ -1538,7 +1538,12 @@ std::vector<ConstantDef*> Impl::GetConstants() const {
 
 static std::string ImplMemberIdentifier(const ImplMember member) {
   return absl::visit(
-      Visitor{[](auto* n) { return n->name_def()->identifier(); }}, member);
+      Visitor{
+          [](const ConstantDef* n) { return n->name_def()->identifier(); },
+          [](const Function* n) { return n->name_def()->identifier(); },
+          [](const VerbatimNode* n) { return std::string("Verbatim"); },
+      },
+      member);
 }
 
 std::optional<ImplMember> Impl::GetMember(std::string_view name) const {
diff --git a/xls/dslx/frontend/ast.h b/xls/dslx/frontend/ast.h
index bb6c83fe15..1fdc12fefb 100644
--- a/xls/dslx/frontend/ast.h
+++ b/xls/dslx/frontend/ast.h
@@ -2611,7 +2611,7 @@ inline std::optional<StructDefBase*> TypeDefinitionToStructDefBase(
   return result == nullptr ? std::nullopt : std::make_optional(result);
 }
 
-using ImplMember = std::variant<ConstantDef*, Function*>;
+using ImplMember = std::variant<ConstantDef*, Function*, VerbatimNode*>;
 
 // Represents an impl for a struct.
 class Impl : public AstNode {
diff --git a/xls/dslx/frontend/ast_cloner.cc b/xls/dslx/frontend/ast_cloner.cc
index 4b6f3dce33..651891742e 100644
--- a/xls/dslx/frontend/ast_cloner.cc
+++ b/xls/dslx/frontend/ast_cloner.cc
@@ -785,10 +785,12 @@ class AstCloner : public AstNodeVisitor {
         XLS_RETURN_IF_ERROR(ReplaceOrVisit(member_node));
       }
       AstNode* new_node = old_to_new_.at(member_node);
-      if (std::holds_alternative<ConstantDef*>(member)) {
-        new_members.push_back(down_cast<ConstantDef*>(new_node));
+      if (auto* new_constant_def = dynamic_cast<ConstantDef*>(new_node)) {
+        new_members.push_back(new_constant_def);
+      } else if (auto* new_function = dynamic_cast<Function*>(new_node)) {
+        new_members.push_back(new_function);
       } else {
-        new_members.push_back(down_cast<Function*>(new_node));
+        new_members.push_back(down_cast<VerbatimNode*>(new_node));
       }
     }
     new_impl->set_members(new_members);