diff --git a/Makefile b/Makefile
index f85046cad..b9942385d 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,20 @@
-CXXFLAGS=-Wall -Wextra -Wshadow -pedantic -Wno-long-long -Wfloat-equal -Wcast-qual -Wsign-conversion -g
-CXX=g++
-BIN=${DESTDIR}/usr/bin
+# This file is generated by tools/dmake, do not edit.
 
-# For 'make man': sudo apt-get install xsltproc docbook-xsl docbook-xml
+ifndef CXXFLAGS
+    CXXFLAGS=-Wall -Wextra -Wshadow -pedantic -Wno-long-long -Wfloat-equal -Wcast-qual -Wsign-conversion -g
+endif
+
+ifndef CXX
+    CXX=g++
+endif
+
+ifndef PREFIX
+    PREFIX=/usr
+endif
+
+BIN=$(DESTDIR)$(PREFIX)/bin
+
+# For 'make man': sudo apt-get install xsltproc docbook-xsl docbook-xml on Linux
 DB2MAN=/usr/share/sgml/docbook/stylesheet/xsl/nwalsh/manpages/docbook.xsl
 XP=xsltproc -''-nonet -''-param man.charmap.use.subset "0"
 MAN_SOURCE=man/cppcheck.1.xml