Add missing file.
diff --git a/include/osmocore/protocol/Makefile.am b/include/osmocore/protocol/Makefile.am
index 6d8883e..557950e 100644
--- a/include/osmocore/protocol/Makefile.am
+++ b/include/osmocore/protocol/Makefile.am
@@ -1,3 +1,3 @@
-osmocore_proto_HEADERS = gsm_04_08.h gsm_04_11.h gsm_04_80.h gsm_08_58.h gsm_12_21.h
+osmocore_proto_HEADERS = gsm_04_08.h gsm_04_11.h gsm_04_80.h gsm_08_58.h gsm_12_21.h gsm_08_08.h
 
 osmocore_protodir = $(includedir)/osmocore/protocol