diff --git a/src/core/CCString.cppo.ml b/src/core/CCString.cppo.ml
index 5c14f724..9c72ae0c 100644
--- a/src/core/CCString.cppo.ml
+++ b/src/core/CCString.cppo.ml
@@ -222,7 +222,7 @@ let find_all ?(start=0) ~sub =
       let res = Find.find ~pattern s !i in
       if res = ~-1 then None
       else (
-        i := res + Find.pattern_length pattern;
+        i := res + 1; (* possible overlap *)
         Some res
       )
 
diff --git a/src/core/CCString.mli b/src/core/CCString.mli
index 930eadc3..79bbbadf 100644
--- a/src/core/CCString.mli
+++ b/src/core/CCString.mli
@@ -109,7 +109,8 @@ val find : ?start:int -> sub:string -> string -> int
 *)
 
 val find_all : ?start:int -> sub:string -> string -> int gen
-(** [find_all ~sub s] finds all occurrences of [sub] in [s]
+(** [find_all ~sub s] finds all occurrences of [sub] in [s], even overlapping
+    instances.
     @param start starting position in [s]
     @since NEXT_RELEASE *)