diff --git a/topology/Makefile.am b/topology/Makefile.am
index 237eb3c..61055d8 100644
--- a/topology/Makefile.am
+++ b/topology/Makefile.am
@@ -13,7 +13,7 @@ endif
 alsatplg_SOURCES = topology.c pre-processor.c pre-process-class.c pre-process-object.c \
 		    pre-process-dapm.c pre-process-dai.c
 
-noinst_HEADERS = topology.h pre-processor.h
+noinst_HEADERS = topology.h pre-processor.h pre-process-external.h
 
 AM_CPPFLAGS = \
          -Wall -I$(top_srcdir)/include -DALSA_TOPOLOGY_PLUGIN_DIR=\"@ALSA_TOPOLOGY_PLUGIN_DIR@\"