diff --git a/_oasis b/_oasis
index 5d3e2909..bd4e8a18 100644
--- a/_oasis
+++ b/_oasis
@@ -53,13 +53,13 @@ Library "containers"
   Path:             src/core
   Modules:          CCVector, CCPrint, CCError, CCHeap, CCList, CCOpt, CCPair,
                     CCFun, CCHash, CCInt, CCBool, CCFloat, CCArray, CCRef, CCSet,
-                    CCOrd, CCRandom, CCString, CCHashtbl, CCMap, CCFormat,
+                    CCOrd, CCRandom, CCString, CCHashtbl, CCMap, CCFormat, CCIO,
                     Containers
   BuildDepends:     bytes
 
 Library "containers_io"
   Path:             src/io
-  Modules:          CCIO
+  Modules:
   BuildDepends:     bytes
   FindlibParent:    containers
   FindlibName:      io
diff --git a/src/advanced/CCMonadIO.ml b/src/advanced/CCMonadIO.ml.cppo
similarity index 100%
rename from src/advanced/CCMonadIO.ml
rename to src/advanced/CCMonadIO.ml.cppo
diff --git a/src/io/CCIO.ml b/src/core/CCIO.ml
similarity index 100%
rename from src/io/CCIO.ml
rename to src/core/CCIO.ml
diff --git a/src/io/CCIO.mli b/src/core/CCIO.mli
similarity index 98%
rename from src/io/CCIO.mli
rename to src/core/CCIO.mli
index 1d079f20..377e7a74 100644
--- a/src/io/CCIO.mli
+++ b/src/core/CCIO.mli
@@ -30,9 +30,6 @@ Simple utilities to deal with basic Input/Output tasks in a resource-safe
 way. For advanced IO tasks, the user is advised to use something
 like Lwt or Async, that are far more comprehensive.
 
-{b NOTE} this was formerly a monadic IO module. The old module is now
-in [containers.advanced] under the name [CCMonadIO].
-
 Examples:
 
 - obtain the list of lines of a file:
@@ -58,6 +55,9 @@ Examples:
 
 @since 0.6
 
+in 'containers' (rather than 'containers.io')
+@since NEXT_RELEASE 
+
 *)