diff --git a/libraries/llvm/forward-declare-c.ll b/libraries/llvm/forward-declare-c.ll
index a34fb1b79..97e18fa88 100644
--- a/libraries/llvm/forward-declare-c.ll
+++ b/libraries/llvm/forward-declare-c.ll
@@ -6,8 +6,8 @@ declare %Pos @c_get_arg(i64)
 declare void @c_io_println(%Pos)
 declare %Pos @c_io_readln()
 
-declare void @hole(i8*)
-declare void @duplicated_prompt()
+declare void @hole(i8*) cold
+declare void @duplicated_prompt() cold
 
 declare %Pos @c_ref_fresh(%Pos)
 declare %Pos @c_ref_get(%Pos)
diff --git a/libraries/llvm/panic.c b/libraries/llvm/panic.c
index 7271f07c7..df9703575 100644
--- a/libraries/llvm/panic.c
+++ b/libraries/llvm/panic.c
@@ -7,11 +7,13 @@
 // this should _morally_ be using `stderr`, but we don't tee it in tests
 // see PR #823 & issue #815 for context
 
+__attribute__((cold))
 void hole(const char* message) {
     printf("PANIC: %s not implemented yet\n", message);
     exit(1);
 }
 
+__attribute__((cold))
 void duplicated_prompt() {
     printf("PANIC: Continuation invoked itself\n");
     exit(1);
diff --git a/libraries/llvm/rts.ll b/libraries/llvm/rts.ll
index 604d75a25..9ea069159 100644
--- a/libraries/llvm/rts.ll
+++ b/libraries/llvm/rts.ll
@@ -407,7 +407,7 @@ define private void @invalidate(%Stack %stack, %Stack %end) {
 
 error:
     call void @duplicated_prompt()
-    ret void
+    unreachable
 
 check:
     %isEnd = icmp eq %Stack %next, %end