diff --git a/lib/dev.ml b/lib/dev.ml
index 0206371..24b2c38 100644
--- a/lib/dev.ml
+++ b/lib/dev.ml
@@ -783,13 +783,12 @@ let locals t ~frame =
                   (name
                    ^ " is not a function this session holds; a lifted handler clause has no declaration of its own to read slot names from")
               | Some fn ->
-                if nslots = 0 then
-                  ok
-                    [ ":frame " ^ Wire.quote name; ":locals ()"; ":refused ()";
-                      ":note "
-                      ^ Wire.quote
-                          "that frame records no slots; every slot in it is one the compiler made up" ]
-                else if nslots <> Array.length fn.Tast.slots then
+                (* The two body checks come first, including for a frame
+                   with no slots. "every slot in it is one the compiler made
+                   up" is a claim about the body this session holds, and a
+                   zero-slot frame whose body has since been replaced by one
+                   with slots is a frame that claim is false about. *)
+                if nslots <> Array.length fn.Tast.slots then
                   error
                     (Printf.sprintf
                        "%s on the stack has %d slots and the %s this session holds has %d: the frame is running a body that has been redefined since, so every slot index here would be a guess"
@@ -807,6 +806,12 @@ let locals t ~frame =
                     (Printf.sprintf
                        "%s on the stack was compiled from a different body than the %s this session holds: this frame's body was redefined since it was entered, so its names no longer describe its values"
                        name name)
+                else if nslots = 0 then
+                  ok
+                    [ ":frame " ^ Wire.quote name; ":locals ()"; ":refused ()";
+                      ":note "
+                      ^ Wire.quote
+                          "that frame records no slots; every slot in it is one the compiler made up" ]
                 else
                   match bound_slots t ~frame with
                   | Error m -> error ("the program refused to say which slots are bound: " ^ m)