diff --git a/transform/func-lowering.go b/transform/func-lowering.go
index 89c9f692..02341a83 100644
--- a/transform/func-lowering.go
+++ b/transform/func-lowering.go
@@ -118,12 +118,18 @@ func LowerFuncValues(mod llvm.Module) {
 						continue
 					}
 					for _, funcValueWithSignatureGlobal := range getUses(funcValueWithSignatureConstant) {
+						id := llvm.ConstInt(uintptrType, uint64(fn.id), false)
 						for _, use := range getUses(funcValueWithSignatureGlobal) {
-							if ptrtoint.IsAConstantExpr().IsNil() || ptrtoint.Opcode() != llvm.PtrToInt {
-								panic("expected const ptrtoint")
+							// Try to replace uses directly: most will be
+							// ptrtoint instructions.
+							if !use.IsAConstantExpr().IsNil() && use.Opcode() == llvm.PtrToInt {
+								use.ReplaceAllUsesWith(id)
 							}
-							use.ReplaceAllUsesWith(llvm.ConstInt(uintptrType, uint64(fn.id), false))
 						}
+						// Remaining uses can be replaced using a ptrtoint.
+						// In my quick testing, this doesn't really happen in
+						// practice.
+						funcValueWithSignatureGlobal.ReplaceAllUsesWith(llvm.ConstIntToPtr(id, funcValueWithSignatureGlobal.Type()))
 					}
 				}
 			}