diff --git a/rules.mk b/rules.mk
index 96a54c9fea832d20a4c22d95bea8e68d3f10d28b..a4dcaa1fcdbd42f1156be727c27d5fa585f55323 100644
--- a/rules.mk
+++ b/rules.mk
@@ -106,9 +106,9 @@ ifneq ($(CONFIG_LARGEFILE),y)
 endif
 
 ifeq ($(CONFIG_TAR_VERBOSITY),y)
-  TAR_OPTIONS=-xvf -
+  TAR_OPTIONS:=-xvf -
 else
-  TAR_OPTIONS=-xf -
+  TAR_OPTIONS:=-xf -
 endif
 
 all: