diff --git a/Makefile.am b/Makefile.am
index f992d25..6101ec9 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -55,6 +55,8 @@ libisofs_libisofs_la_SOURCES = \
 	libisofs/iso1999.h \
 	libisofs/iso1999.c \
 	libisofs/data_source.c
+libisofs_libisofs_la_LIBADD= \
+	$(THREAD_LIBS)
 libinclude_HEADERS = \
 	libisofs/libisofs.h