diff --git a/tools/build/onos-buck b/tools/build/onos-buck
index 70c4414..ff8893c 100755
--- a/tools/build/onos-buck
+++ b/tools/build/onos-buck
@@ -5,11 +5,11 @@
 
 set -e
 
-BUCK_URL="http://repo1.maven.org/maven2/org/onosproject/onos-buck/v2018.02.09.01/buck-v2018.02.09.01.zip"
-BUCK_SHA="45d8bd28f441991257babf89f7a317edb3a2b536"
+BUCK_URL="http://repo1.maven.org/maven2/org/onosproject/onos-buck/v2018.01.17.01/buck-v2018.01.17.01.zip"
+BUCK_SHA="4a70a84ef40a06762a7248db25590696e80af9fe"
 
 # onos-yang-tools buck plugin version
-YANG_VER="2.4.1"
+YANG_VER="2.3.1"
 
 [  "-U" = "$1" ] && shift && FORCE_UPDATE=True
 
diff --git a/tools/dev/bin/patch-yang-libs b/tools/dev/bin/patch-yang-libs
index 2686836..fd119b3 100755
--- a/tools/dev/bin/patch-yang-libs
+++ b/tools/dev/bin/patch-yang-libs
@@ -3,8 +3,8 @@
 # Patches lib/BUCK file to use locally built YANG tools.
 # -----------------------------------------------------------------------------
 
-BVER=2.4
-SVER=2.5-SNAPSHOT
+BVER=2.3.1
+SVER=2.4-SNAPSHOT
 
 YANG_TOOLS_ROOT=${YANG_TOOLS_ROOT:-~/onos-yang-tools}