diff --git a/.hgtags b/.hgtags
index 7929be9..d2cc339 100644
--- a/.hgtags
+++ b/.hgtags
@@ -3,3 +3,4 @@
 137c1b65039e03c80379826a6efdfd808f6fbc8f libnmdc-r2
 d8b64d5527c2a5e4d76872e5bc3d69f7646135c6 libnmdc-r3
 fca41372e400853775b02e951f9db91d87f41adb nmdc-log-service-1.0.1
+050b424a7c5d5a27c9323c8810f3afbead1f5b96 libnmdc-r4