diff --git a/test/lib/Makefile b/test/lib/Makefile
index 308c617..b13aaca 100644
--- a/test/lib/Makefile
+++ b/test/lib/Makefile
@@ -6,3 +6,4 @@
 obj-y += hexdump.o
 obj-y += lmb.o
 obj-y += string.o
+obj-$(CONFIG_ERRNO_STR) += test_errno_str.o