--- a/configure
+++ b/configure
@@ -23,10 +23,10 @@
 build=no
 check=no
 installdir=
-CXX=g++
-CPPFLAGS=
-CXXFLAGS='-Wall -W -O2'
-LDFLAGS=
+CXX?=g++
+CPPFLAGS?=
+CXXFLAGS?='-Wall -W -O2'
+LDFLAGS?=
 MAKEINFO=makeinfo
 
 # checking whether we are using GNU C++.