diff --git a/src/makefile.osx b/src/makefile.osx
index 4836ea3f4..1e6993d69 100644
--- a/src/makefile.osx
+++ b/src/makefile.osx
@@ -47,7 +47,7 @@ OBJS= \
     cryptopp/obj/sha.o \
     cryptopp/obj/cpu.o
 
-ifdef USE_UPNP
+ifeq (USE_UPNP, 1)
 	LIBS += $(DEPSDIR)/lib/libminiupnpc.a
 	DEFS += -DUSE_UPNP=$(USE_UPNP)
 endif