diff --git a/httpuv/src/Makevars.in b/httpuv/src/Makevars.in
index f3b1af0..e000e1f 100644
--- a/httpuv/src/Makevars.in
+++ b/httpuv/src/Makevars.in
@@ -1,6 +1,6 @@
 UNAME := $(shell uname)
 
-PKG_LIBS = @libs@ ./http-parser/http_parser.o ./sha1/sha1.o ./base64/base64.o -pthread
+PKG_LIBS = @libs@ -lz ./http-parser/http_parser.o ./sha1/sha1.o ./base64/base64.o -pthread
 
 ifeq ($(UNAME), Darwin)
 PKG_LIBS += -framework CoreServices