diff --git a/include/Makefile.am b/include/Makefile.am
index 4c49ce98c..fd5854270 100644
--- a/include/Makefile.am
+++ b/include/Makefile.am
@@ -24,6 +24,7 @@ CLEANFILES =			\
 	digest_asn1.h 		\
 	hdb-protos.h		\
 	heim_asn1.h		\
+	heim_threads.h		\
 	hex.h			\
 	hx509-protos.h		\
 	hx509.h			\