diff --git a/.github/lexicon.txt b/.github/lexicon.txt
index a4c02373eb8..1a7d4852dc2 100644
--- a/.github/lexicon.txt
+++ b/.github/lexicon.txt
@@ -1,3 +1,4 @@
+  GNU nano 5.9                     .github/lexicon.txt                     Modified
 aa
 aaaa
 aarch
@@ -317,6 +318,7 @@ coproc
 coprocessor
 coprocessors
 coreid
+coroutinehandle
 covfs
 cp
 cpacr
@@ -338,15 +340,32 @@ cprivilegedonlyaccessarray
 cpsid
 cpsie
 cpsr
+cpsr
+cpstored
 cpstored
 cpu
+cpu
 cr
+cr
+crc
 crc
 crcb
+crcoroutine
+crcoroutine
+crdelay
+crdelay
 creadonlyarray
 creadwritearray
 createevent
+crend
+crend
 crgint
+croutine
+croutine
+crqueue
+crqueue
+crstart
+crstart
 crt
 crtv
 crxedchar
@@ -1523,11 +1542,17 @@ prvaddcurrenttasktodelayedlist
 prvcheckinterfaces
 prvchecktaskswaitingtermination
 prvcopydatatoqueue
+prvcoroutineflashtask
+prvcoroutineflashtask
+prvcoroutineflashworktask
+prvcoroutineflashworktask
 prvdeletetcb
 prvexitfunction
 prvgettimens
 prvheapinit
 prvidletask
+prvinitialisecoroutinelists
+prvinitialisecoroutinelists
 prvinitialisemutex
 prvinitialisenewstreambuffer
 prvinitialisenewtimer
@@ -1642,11 +1667,18 @@ pxblocktoinsert
 pxcallbackfunction
 pxcode
 pxcontainer
+pxcoroutinecode
+pxcoroutinecode
+pxcoroutinewoken
+pxcoroutinewoken
 pxcrcb
 pxcreatedtask
+pxcurrentcoroutine
+pxcurrentcoroutine
 pxcurrenttcb
 pxcurrenttcbconst
 pxcurrenttimerlist
+pxdelayedcoroutinelist
 pxdelayedtasklist
 pxend
 pxendofstack
@@ -1681,6 +1713,7 @@ pxnextfreeblock
 pxnexttcb
 pxoriginalsp
 pxoriginaltos
+pxoverflowdelayedcoroutinelist
 pxoverflowdelayedtasklist
 pxowner
 pxportinitialisestack
@@ -1690,6 +1723,7 @@ pxqueue
 pxqueuebuffer
 pxqueuesetcontainer
 pxramstack
+pxreadycoroutinelists
 pxreadytaskslists
 pxreceivecompletedcallback
 pxregions
@@ -2463,6 +2497,7 @@ uxtopreadypriority
 uxtopusedpriority
 uxvariabletoincrement
 uxwantedbytes
+vacoroutine
 vadifferenttask
 vafunction
 val
@@ -2492,6 +2527,7 @@ vbr
 vbufferisr
 vcallbackfunction
 vclearinterruptmask
+vcoroutineschedule
 vddcore
 vec
 vectactive
@@ -2501,6 +2537,7 @@ ver
 veventgroupclearbitscallback
 veventgroupdelete
 veventgroupsetbitscallback
+vflashcoroutine
 vfp
 vfunction
 vic
@@ -2563,12 +2600,14 @@ vqueuedelete
 vqueueunregisterqueue
 vr
 vraiseprivilege
+vreceivingcoroutine
 vreg
 vresetprivilege
 vrestorecontextoffirsttask
 vrpm
 vsemaphorecreatebinary
 vsemaphoredelete
+vsendingcoroutine
 vsetbacklightstate
 vsoftwareinterruptentry
 vstartfirsttask
@@ -2702,6 +2741,9 @@ xcommandtime
 xcommsrxqueue
 xconsttickcount
 xcopyposition
+xcoroutinecreate
+xcoroutinepreviouslywoken
+xcoroutinequeue
 xcount
 xcreatedeventgroup
 xcrwokenbypost
@@ -2711,6 +2753,7 @@ xdd
 xdddd
 xdeadbeef
 xdelay
+xdelayedcoroutinelist
 xdelayedtasklist
 xdelaytime
 xe
@@ -2859,6 +2902,7 @@ xpar
 xparameters
 xpendedcounts
 xpendedticks
+xpendingreadycoroutinelist
 xpendingreadylist
 xperiod
 xportgetcoreid
@@ -3100,4 +3144,3 @@ xwritevalue
 xxr
 xyieldpending
 xzr
-
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d45de64b1b5..46a9e180796 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -267,6 +267,7 @@ add_compile_options(
 add_subdirectory(portable)
 
 add_library(freertos_kernel STATIC
+    croutine.c
     event_groups.c
     list.c
     queue.c
diff --git a/README.md b/README.md
index 952914daf46..dd79eee6ce7 100644
--- a/README.md
+++ b/README.md
@@ -70,7 +70,8 @@ git clone git@github.com:FreeRTOS/FreeRTOS-Kernel.git
 ## Repository structure
 - The root of this repository contains the three files that are common to
 every port - list.c, queue.c and tasks.c.  The kernel is contained within these
-three files.
+three files.  croutine.c implements the optional co-routine functionality - which
+is normally only used on very memory limited systems.
 
 - The ```./portable``` directory contains the files that are specific to a particular microcontroller and/or compiler.
 See the readme file in the ```./portable``` directory for more information.