diff --git a/defaults.mk b/defaults.mk
index 03f960b..bfd8165 100644
--- a/defaults.mk
+++ b/defaults.mk
@@ -16,11 +16,11 @@ CFLAGS_release += -g -O3
 LDFLAGS_release += -g -O3
 
 # Environment
-NM=nm
-RANLIB=ranlib
-CC=gcc
-CCC=g++
-CXX=g++
-AS=as
+NM ?= nm
+RANLIB ?= ranlib
+CC ?= gcc
+CCC ?= g++
+CXX ?= g++
+AS ?= as
 
 BUILD_DIR ?= $(PWD)/build/$(ARCH)/${CONFIG}
diff --git a/defaults.win.mk b/defaults.win.mk
index ce12927..94752c6 100644
--- a/defaults.win.mk
+++ b/defaults.win.mk
@@ -20,11 +20,11 @@ CFLAGS_release := -g -O3
 LDFLAGS_release := -g -O3
 
 # Environment
-NM=i686-w64-mingw32-nm
-RANLIB=i686-w64-mingw32-ranlib
-CC=i686-w64-mingw32-gcc
-CCC=i686-w64-mingw32-g++
-CXX=i686-w64-mingw32-g++
-AS=i686-w64-mingw32-as
+NM ?= i686-w64-mingw32-nm
+RANLIB ?= i686-w64-mingw32-ranlib
+CC ?= i686-w64-mingw32-gcc
+CCC ?= i686-w64-mingw32-g++
+CXX ?= i686-w64-mingw32-g++
+AS ?= i686-w64-mingw32-as
 
 BUILD_DIR ?= $(PWD)/build/$(ARCH)/${CONFIG}