Prefer C linkage
diff --git a/src/Makefile.am b/src/Makefile.am
index a8ba69c..409c939 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -113,6 +113,7 @@
 main_LDADD = libharfbuzz.la $(HBLIBS)
 
 TESTS = \
+	check-c-linkage-decls.sh \
 	check-header-guards.sh \
 	check-internal-symbols.sh \
 	$(NULL)