diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,6 +9,13 @@
   SET(LEMON_VERSION $ENV{LEMON_VERSION} CACHE STRING "LEMON version string.")
 ELSE()
   EXECUTE_PROCESS(
+    COMMAND ./scripts/chg-len.py
+    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+    OUTPUT_VARIABLE HG_REVISION_PATH
+    ERROR_QUIET
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+  )
+  EXECUTE_PROCESS(
     COMMAND hg id -i
     WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
     OUTPUT_VARIABLE HG_REVISION
@@ -16,9 +23,11 @@
     OUTPUT_STRIP_TRAILING_WHITESPACE
   )
   IF(HG_REVISION STREQUAL "")
-    SET(HG_REVISION "hg-tip")
+    SET(HG_REVISION_ID "hg-tip")
+  ELSE()
+    SET(HG_REVISION_ID ${HG_REVISION_PATH}.${HG_REVISION})
   ENDIF()
-  SET(LEMON_VERSION ${HG_REVISION} CACHE STRING "LEMON version string.")
+  SET(LEMON_VERSION ${HG_REVISION_ID} CACHE STRING "LEMON version string.")
 ENDIF()
 
 SET(PROJECT_VERSION ${LEMON_VERSION})