--- bind/isc-config.sh.in
+++ bind/isc-config.sh.in
@@ -115,7 +115,7 @@ if test x"$echo_exec_prefix" = x"true" ; then
 	echo $exec_prefix
 fi
 if test x"$echo_cflags" = x"true"; then
-	includes="-I${exec_prefix}/include"
+	[ "$exec_prefix" = /usr ] || includes="-I${exec_prefix}/include"
 	if test x"$libisc" = x"true"; then
 		includes="$includes @ALWAYS_DEFINES@ @STD_CINCLUDES@ @STD_CDEFINES@ @CCOPT@"
 	fi