diff --git a/Makefile.am b/Makefile.am
index a41f959c..a0b11d5e 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -233,6 +233,7 @@ array_test_SOURCES = tests/array-test.c
 array_test_LDADD = libtest-runner.la
 client_test_SOURCES = tests/client-test.c
 client_test_LDADD = libtest-runner.la
+display_test_CFLAGS = -pthread
 display_test_SOURCES = tests/display-test.c
 display_test_LDADD = libtest-runner.la
 nodist_display_test_SOURCES =				\