diff --git a/Makefile b/Makefile
index 7d7a1644dbd07234c40e54578a7fe22a6d9fd631..4359bc6ee21d4cad2f437fef3539a8fd1bfc6046 100644
--- a/Makefile
+++ b/Makefile
@@ -2,8 +2,8 @@ include $(FSLCONFDIR)/default.mk
 
 PROJNAME = slicetimer
 
-USRINCFLAGS = -I${INC_NEWMAT} -I${INC_PROB}
-USRLDFLAGS = -L${LIB_NEWMAT} -L${LIB_PROB}
+USRINCFLAGS = -I${INC_NEWMAT} -I${INC_PROB} -I${INC_ZLIB}
+USRLDFLAGS = -L${LIB_NEWMAT} -L${LIB_PROB} -L${LIB_ZLIB}
 
 OBJS = slicetimer.o