diff --git a/hs20/server/Makefile b/hs20/server/Makefile
index 587633b..248ed5c 100644
--- a/hs20/server/Makefile
+++ b/hs20/server/Makefile
@@ -12,6 +12,7 @@
 CFLAGS = -MMD -O2 -Wall -g
 endif
 
+CFLAGS += -I../../src
 CFLAGS += -I../../src/utils
 CFLAGS += -I../../src/crypto