diff --git a/fastbuild/README.md b/fastbuild/README.md
index ccc2282..86ed568 100644
--- a/fastbuild/README.md
+++ b/fastbuild/README.md
@@ -20,6 +20,8 @@ board.
 
 The scripts will require minor edits to reflect your directory structure.
 
+Scripts updated 12 Sep 2021 to fix handling of submodules.
+
 ###### [Main README](../README.md)
 
 # Frozen modules and manifests
diff --git a/fastbuild/buildesp b/fastbuild/buildesp
index a81e7dd..b3ae598 100755
--- a/fastbuild/buildesp
+++ b/fastbuild/buildesp
@@ -19,6 +19,7 @@ then
     fi
 fi
 
+make submodules
 if make -j 8 FROZEN_MANIFEST=$MANIFEST
 then
     sleep 1
diff --git a/fastbuild/buildnew b/fastbuild/buildnew
index 5b9d577..6ef8e76 100755
--- a/fastbuild/buildnew
+++ b/fastbuild/buildnew
@@ -5,6 +5,7 @@ cd $MPDIR
 echo Working...
 git checkout master
 git pull origin master --tags
+git submodule sync
 git submodule update --init
 cd mpy-cross
 make clean
@@ -20,6 +21,5 @@ cd ../esp8266
 make clean
 cd ../unix
 make clean
-# If you're going to enable deplibs: see micropython/README
-#make deplibs
+make submodules
 make -j 8
diff --git a/fastbuild/buildpyb b/fastbuild/buildpyb
index b9731d0..b2ef11e 100755
--- a/fastbuild/buildpyb
+++ b/fastbuild/buildpyb
@@ -39,6 +39,7 @@ then
     then
         make BOARD=$BOARD clean
     fi
+    make submodules
     if make -j 8 BOARD=$BOARD FROZEN_MANIFEST=$MANIFEST MICROPY_VFS_LFS2=1 && pyb_boot $MPDEVICE
     then
         sleep 1