diff --git a/utils/misc.ml b/utils/misc.ml
index 4db31452cb8f..10a3637fe55b 100644
--- a/utils/misc.ml
+++ b/utils/misc.ml
@@ -156,9 +156,7 @@ module Stdlib = struct
       | [], [] -> true
       | _::_, [] -> false
       | [], _::_ -> true
-      | x1::t, x2::of_ ->
-        if equal x1 x2 then is_prefix ~equal t ~of_
-        else false
+      | x1::t, x2::of_ -> equal x1 x2 && is_prefix ~equal t ~of_
 
     type 'a longest_common_prefix_result = {
       longest_common_prefix : 'a list;
@@ -169,24 +167,14 @@ module Stdlib = struct
     let find_and_chop_longest_common_prefix ~equal ~first ~second =
       let rec find_prefix ~longest_common_prefix_rev l1 l2 =
         match l1, l2 with
-        | [], []
-        | [], _::_
-        | _::_, [] ->
-          let longest_common_prefix = List.rev longest_common_prefix_rev in
-          { longest_common_prefix;
+        | elt1 :: l1, elt2 :: l2 when equal elt1 elt2 ->
+          let longest_common_prefix_rev = elt1 :: longest_common_prefix_rev in
+          find_prefix ~longest_common_prefix_rev l1 l2
+        | l1, l2 ->
+          { longest_common_prefix = List.rev longest_common_prefix_rev;
             first_without_longest_common_prefix = l1;
             second_without_longest_common_prefix = l2;
           }
-        | elt1::l1_tail, elt2::l2_tail ->
-          if equal elt1 elt2 then
-            let longest_common_prefix_rev = elt1 :: longest_common_prefix_rev in
-            find_prefix ~longest_common_prefix_rev l1_tail l2_tail
-          else
-            let longest_common_prefix = List.rev longest_common_prefix_rev in
-            { longest_common_prefix;
-              first_without_longest_common_prefix = l1;
-              second_without_longest_common_prefix = l2;
-            }
       in
       find_prefix ~longest_common_prefix_rev:[] first second
   end
diff --git a/utils/misc.mli b/utils/misc.mli
index 4ce61b431ac7..7c724f2bfda4 100644
--- a/utils/misc.mli
+++ b/utils/misc.mli
@@ -117,13 +117,13 @@ module Stdlib : sig
         the [n] first elements of [l] and [after] the remaining ones.
         If [l] has less than [n] elements, raises Invalid_argument. *)
 
-    (** Returns [true] iff the given list, with respect to the given equality
-        function on list members, is a prefix of the list [of_]. *)
     val is_prefix
        : equal:('a -> 'a -> bool)
       -> 'a list
       -> of_:'a list
       -> bool
+    (** Returns [true] iff the given list, with respect to the given equality
+        function on list members, is a prefix of the list [of_]. *)
 
     type 'a longest_common_prefix_result = private {
       longest_common_prefix : 'a list;
@@ -131,14 +131,14 @@ module Stdlib : sig
       second_without_longest_common_prefix : 'a list;
     }
 
-    (** Returns the longest list that, with respect to the provided equality
-        function, is a prefix of both of the given lists.  The input lists,
-        each with such longest common prefix removed, are also returned. *)
     val find_and_chop_longest_common_prefix
        : equal:('a -> 'a -> bool)
       -> first:'a list
       -> second:'a list
       -> 'a longest_common_prefix_result
+    (** Returns the longest list that, with respect to the provided equality
+        function, is a prefix of both of the given lists.  The input lists,
+        each with such longest common prefix removed, are also returned. *)
   end
 
   module Option : sig