diff --git a/src/CodeGen_C.cpp b/src/CodeGen_C.cpp
index dfa1b73564a9..a29f2a78290c 100644
--- a/src/CodeGen_C.cpp
+++ b/src/CodeGen_C.cpp
@@ -275,10 +275,6 @@ class TypeInfoGatherer : public IRGraphVisitor {
         include_type(op->type);
         if (op->is_intrinsic(Call::lerp)) {
             // lower_lerp() can synthesize wider vector types.
-            // It's not safe to feed temporary Exprs into IRGraphVisitor
-            // (it tracks the seen values by IRNode*, which could get recycled
-            // if we are unlucky), so just add widened versions of any
-            // types present -- it's safe to add types we might not use.
             for (auto &a : op->args) {
                 include_lerp_types(a.type());
             }
diff --git a/src/IRVisitor.h b/src/IRVisitor.h
index 70d7d2f43f26..d24cc609426f 100644
--- a/src/IRVisitor.h
+++ b/src/IRVisitor.h
@@ -92,7 +92,7 @@ class IRGraphVisitor : public IRVisitor {
 
 private:
     /** The nodes visited so far */
-    std::set<const IRNode *> visited;
+    std::set<IRHandle> visited;
 
 protected:
     /** These methods should call 'include' on the children to only