diff --git a/lib/isc/Makefile.am b/lib/isc/Makefile.am
index 58438d5c5e..3d2e891db2 100644
--- a/lib/isc/Makefile.am
+++ b/lib/isc/Makefile.am
@@ -221,7 +221,8 @@ libisc_la_SOURCES =		\
 	entropy_private.h	\
 	fsaccess_common_p.h	\
 	mem_p.h			\
-	task_p.h
+	task_p.h		\
+	tls_p.h
 
 libisc_la_CPPFLAGS =		\
 	$(AM_CPPFLAGS)		\