--- a/makefile.rules.orig	2012-05-09 21:03:28.000000000 +0200
+++ b/makefile.rules	2012-05-09 21:03:56.000000000 +0200
@@ -9,6 +9,8 @@
 #   SRC_DIR needs to be passed in.  It is assumed that make is running in
 #   the build directory.
 
+CC ?= gcc
+
 #*******************************************************************************
 #                               Environment
 
@@ -101,7 +103,7 @@
 	keygen.o
 
 
-LIBS =     -lstdc++
+LIBS ?=     -lstdc++ -lm
 
 
 ifeq ("${UNAMES}", "Linux")
@@ -137,13 +139,13 @@
 		${EXEC_FILE_ELFTOSB2} ${EXEC_FILE_SBTOOL} ${EXEC_FILE_KEYGEN}
 
 elftosb: ${OBJ_FILES_ELFTOSB2}
-	gcc ${OBJ_FILES_ELFTOSB2} ${LIBS} -o ${EXEC_FILE_ELFTOSB2}
+	${CC} ${OBJ_FILES_ELFTOSB2} ${LIBS} -o ${EXEC_FILE_ELFTOSB2}
 
 sbtool: ${OBJ_FILES_SBTOOL}
-	gcc ${OBJ_FILES_SBTOOL} ${LIBS} -o ${EXEC_FILE_SBTOOL}
+	${CC} ${OBJ_FILES_SBTOOL} ${LIBS} -o ${EXEC_FILE_SBTOOL}
 
 keygen: ${OBJ_FILES_KEYGEN}
-	gcc ${OBJ_FILES_KEYGEN} ${LIBS} -o ${EXEC_FILE_KEYGEN}
+	${CC} ${OBJ_FILES_KEYGEN} ${LIBS} -o ${EXEC_FILE_KEYGEN}
 
 
 #ifeq ("${UNAMES}", "Linux")
@@ -153,10 +155,10 @@
 .SUFFIXES : .c .cpp
 
 .c.o :
-	gcc ${CFLAGS} -c $<
+	${CC} ${CFLAGS} -c $<
 
 .cpp.o :
-	gcc ${CFLAGS} -c $<
+	${CC} ${CFLAGS} -c $<
 
 #endif