diff --git a/stdlib/string.mli b/stdlib/string.mli
index 8d2772dd2203..600669e11388 100644
--- a/stdlib/string.mli
+++ b/stdlib/string.mli
@@ -132,8 +132,8 @@ val concat : string -> string list -> string
 val cat : string -> string -> string
 (** [cat s1 s2] concatenates s1 and s2 ([s1 ^ s2]).
 
-    @raise Invalid_argument if the result is longer then
-    than {!Sys.max_string_length} bytes.
+    @raise Invalid_argument if the result is longer than
+    {!Sys.max_string_length} bytes.
 
     @since 4.13
 *)
diff --git a/stdlib/stringLabels.mli b/stdlib/stringLabels.mli
index aa2056be3c1b..c73ce7eece49 100644
--- a/stdlib/stringLabels.mli
+++ b/stdlib/stringLabels.mli
@@ -132,8 +132,8 @@ val concat : sep:string -> string list -> string
 val cat : string -> string -> string
 (** [cat s1 s2] concatenates s1 and s2 ([s1 ^ s2]).
 
-    @raise Invalid_argument if the result is longer then
-    than {!Sys.max_string_length} bytes.
+    @raise Invalid_argument if the result is longer than
+    {!Sys.max_string_length} bytes.
 
     @since 4.13
 *)