diff --git a/make/defs.mk b/make/defs.mk
index 59435e39..d575c520 100644
--- a/make/defs.mk
+++ b/make/defs.mk
@@ -110,8 +110,8 @@ CPPFLAGS              += -DVERSION=$(HEX_VERSION)
 LD_LIB_PATH           += $(MODDIR)/lib
 
 ifeq ($(TARGET),mingw)
-CROSS_TOOL_DIR         = /opt/cross-tools
-CROSS_TOOL_BIN_PREFIX  = $(CROSS_TOOL_DIR)/bin/i386-mingw32-
+CROSS_TOOL_DIR        ?= /opt/cross-tools
+CROSS_TOOL_BIN_PREFIX ?= $(CROSS_TOOL_DIR)/bin/i386-mingw32-
 GCC                    = $(CROSS_TOOL_BIN_PREFIX)gcc
 GPP                    = $(CROSS_TOOL_BIN_PREFIX)g++
 STRIP                  = $(CROSS_TOOL_BIN_PREFIX)strip