diff --git a/src/makefile.linux-mingw b/src/makefile.linux-mingw
index fa46d080bb1..41dbf2a9fc0 100644
--- a/src/makefile.linux-mingw
+++ b/src/makefile.linux-mingw
@@ -53,7 +53,10 @@ HEADERS = \
     wallet.h
 
 
-ifdef USE_UPNP
+ifndef USE_UPNP
+	override USE_UPNP = -
+endif
+ifneq (${USE_UPNP}, -)
 	LIBPATHS += -L"$(DEPSDIR)/miniupnpc"
 	LIBS += -l miniupnpc -l iphlpapi
 	DEFS += -DSTATICLIB -DUSE_UPNP=$(USE_UPNP)
diff --git a/src/makefile.mingw b/src/makefile.mingw
index 5e9a4427f14..75d3992f8ae 100644
--- a/src/makefile.mingw
+++ b/src/makefile.mingw
@@ -49,7 +49,10 @@ HEADERS = \
     util.h \
     wallet.h
 
-ifdef USE_UPNP
+ifndef USE_UPNP
+	override USE_UPNP = -
+endif
+ifneq (${USE_UPNP}, -)
  INCLUDEPATHS += -I"C:\miniupnpc-1.6-mgw"
  LIBPATHS += -L"C:\miniupnpc-1.6-mgw"
  LIBS += -l miniupnpc -l iphlpapi
diff --git a/src/makefile.osx b/src/makefile.osx
index cbd51b049f0..5e9236fd739 100644
--- a/src/makefile.osx
+++ b/src/makefile.osx
@@ -91,7 +91,10 @@ OBJS= \
     obj/util.o \
     obj/wallet.o
 
-ifdef USE_UPNP
+ifndef USE_UPNP
+	override USE_UPNP = -
+endif
+ifneq (${USE_UPNP}, -)
 	DEFS += -DUSE_UPNP=$(USE_UPNP)
 ifdef STATIC
 	LIBS += $(DEPSDIR)/lib/libminiupnpc.a