diff --git a/Makefile b/Makefile
index 9dc42e7..6eb3efc 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,9 @@
 PACKAGE	= utils
 VERSION	= 0.0.3
 SUBDIRS	= src tools
-RM	= rm -f
-LN	= ln -f
-TAR	= tar -czvf
+RM	?= rm -f
+LN	?= ln -f
+TAR	?= tar -czvf
 
 
 all: subdirs
diff --git a/src/Makefile b/src/Makefile
index b188f5d..2512b6f 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -3,14 +3,14 @@ PREFIX	= /usr/local
 DESTDIR	=
 BINDIR	= $(PREFIX)/bin
 CC	= cc
-CPPFLAGSF=
-CPPFLAGS=
+CPPFLAGSF?=
+CPPFLAGS?=
 CFLAGSF	= -W
 CFLAGS	= -Wall -g -O2 -pedantic
-RM	= rm -f
-LN	= ln -f
-MKDIR	= mkdir -p
-INSTALL	= install
+RM	?= rm -f
+LN	?= ln -f
+MKDIR	?= mkdir -p
+INSTALL	?= install
 
 
 all: $(TARGETS)
diff --git a/tools/Makefile b/tools/Makefile
index 4a1d928..9e9146e 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -3,14 +3,14 @@ PREFIX	= /usr/local
 DESTDIR	=
 BINDIR	= $(PREFIX)/bin
 CC	= cc
-CPPFLAGSF=
-CPPFLAGS=
+CPPFLAGSF?=
+CPPFLAGS?=
 CFLAGSF	= -W
 CFLAGS	= -Wall -g -O2 -pedantic
-RM	= rm -f
-LN	= ln -f
-MKDIR	= mkdir -p
-INSTALL	= install
+RM	?= rm -f
+LN	?= ln -f
+MKDIR	?= mkdir -p
+INSTALL	?= install
 
 
 all: $(TARGETS)