diff --git a/src/build/roc/Builtin.roc b/src/build/roc/Builtin.roc
index a041b4ed32..e77e1f7e78 100644
--- a/src/build/roc/Builtin.roc
+++ b/src/build/roc/Builtin.roc
@@ -331,15 +331,15 @@ Builtin :: [].{
 			from_numeral : Numeral -> Try(U8, [InvalidNumeral(Str), ..others])
 			from_str : Str -> Try(U8, [BadNumStr, ..others])
 
-			## List of integers beginning with this `U8` and ending with the other `U8`.
-			## (Use [until] instead to end with the other `U8` minus one.)
-			## Returns an empty list if this `U8` is greater than the other.
+			# # List of integers beginning with this `U8` and ending with the other `U8`.
+			# # (Use [until] instead to end with the other `U8` minus one.)
+			# # Returns an empty list if this `U8` is greater than the other.
 			to : U8, U8 -> List(U8)
 			to = |start, end| range_to(start, end)
 
-			## List of integers beginning with this `U8` and ending with the other `U8` minus one.
-			## (Use [to] instead to end with the other `U8` exactly, instead of minus one.)
-			## Returns an empty list if this `U8` is greater than or equal to the other.
+			# # List of integers beginning with this `U8` and ending with the other `U8` minus one.
+			# # (Use [to] instead to end with the other `U8` exactly, instead of minus one.)
+			# # Returns an empty list if this `U8` is greater than or equal to the other.
 			until : U8, U8 -> List(U8)
 			until = |start, end| range_until(start, end)
 
@@ -990,25 +990,25 @@ Builtin :: [].{
 }
 
 range_to = |var $current, end| {
-    var $answer = [] # Not bothering with List.with_capacity because this will become an iterator once those exist.
+	var $answer = [] # Not bothering with List.with_capacity because this will become an iterator once those exist.
 
-    while $current <= end {
-        $answer = $answer.append($current)
-        $current = $current + 1
-    }
+	while $current <= end {
+		$answer = $answer.append($current)
+		$current = $current + 1
+	}
 
-    $answer
+	$answer
 }
 
 range_until = |var $current, end| {
-    var $answer = [] # Not bothering with List.with_capacity because this will become an iterator once those exist.
+	var $answer = [] # Not bothering with List.with_capacity because this will become an iterator once those exist.
 
-    while $current < end {
-        $answer = $answer.append($current)
-        $current = $current + 1
-    }
+	while $current < end {
+		$answer = $answer.append($current)
+		$current = $current + 1
+	}
 
-    $answer
+	$answer
 }
 
 # Implemented by the compiler, does not perform bounds checks
diff --git a/src/eval/interpreter.zig b/src/eval/interpreter.zig
index fc250d1fa2..0abc93cf29 100644
--- a/src/eval/interpreter.zig
+++ b/src/eval/interpreter.zig
@@ -1481,13 +1481,15 @@ pub const Interpreter = struct {
                 // Get the result layout - should be List(U8).
                 // If return_rt_var is a flex that would default to a scalar,
                 // we need to ensure we get a proper list layout for correct refcounting.
+                const result_rt_var = return_rt_var orelse {
+                    self.triggerCrash("str_to_utf8 requires return type info", false, roc_ops);
+                    return error.Crash;
+                };
                 const result_layout = blk: {
-                    if (return_rt_var) |rt_var| {
-                        const maybe_layout = try self.getRuntimeLayout(rt_var);
-                        // If the layout is a list, use it
-                        if (maybe_layout.tag == .list or maybe_layout.tag == .list_of_zst) {
-                            break :blk maybe_layout;
-                        }
+                    const maybe_layout = try self.getRuntimeLayout(result_rt_var);
+                    // If the layout is a list, use it
+                    if (maybe_layout.tag == .list or maybe_layout.tag == .list_of_zst) {
+                        break :blk maybe_layout;
                     }
                     // Fallback: create a proper List(U8) layout
                     const u8_layout_idx = try self.runtime_layout_store.insertLayout(Layout.int(.u8));