diff --git a/common/CMakeLists.txt b/common/CMakeLists.txt
index e43c240ae..d7373115f 100644
--- a/common/CMakeLists.txt
+++ b/common/CMakeLists.txt
@@ -1,3 +1,7 @@
+# CMakeLists for common directory
+#
+# provides the common library
+
 CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
 add_subdirectory(pb)
 
diff --git a/common/pb/CMakeLists.txt b/common/pb/CMakeLists.txt
index b654443e9..455f161fe 100644
--- a/common/pb/CMakeLists.txt
+++ b/common/pb/CMakeLists.txt
@@ -1,3 +1,7 @@
+# CMakeLists for common directory
+#
+# provides the protobuf interfaces
+
 CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
 
 SET(PROTO_FILES