diff --git a/proxy/http2/Makefile.am b/proxy/http2/Makefile.am
index d9e2f64d779..d34de7015bd 100644
--- a/proxy/http2/Makefile.am
+++ b/proxy/http2/Makefile.am
@@ -62,12 +62,14 @@ check_PROGRAMS = \
 
 TESTS = $(check_PROGRAMS)
 
+# The order of libinkevent.a and libhdrs.a is sensitive for LLD on debug build.
+# Be careful if you change the order. Details in GitHub #6666
 test_libhttp2_LDADD = \
 	libhttp2.a \
+	$(top_builddir)/iocore/eventsystem/libinkevent.a \
 	$(top_builddir)/proxy/hdrs/libhdrs.a \
 	$(top_builddir)/src/tscore/libtscore.la \
 	$(top_builddir)/src/tscpp/util/libtscpputil.la \
-	$(top_builddir)/iocore/eventsystem/libinkevent.a \
 	$(top_builddir)/lib/records/librecords_p.a \
 	$(top_builddir)/mgmt/libmgmt_p.la \
 	$(top_builddir)/proxy/shared/libUglyLogStubs.a \