diff --git a/include/unpack.mk b/include/unpack.mk
index e2810944e8..2cd17817e6 100644
--- a/include/unpack.mk
+++ b/include/unpack.mk
@@ -67,10 +67,10 @@ ifeq ($(strip $(UNPACK_CMD)),)
 endif
 
 ifdef PKG_BUILD_DIR
-  PKG_UNPACK := $(call UNPACK_CMD,$(PKG_BUILD_DIR)) $(call CRLF_CMD,$(PKG_BUILD_DIR))
+  PKG_UNPACK ?= $(call UNPACK_CMD,$(PKG_BUILD_DIR)) $(call CRLF_CMD,$(PKG_BUILD_DIR))
 endif
 ifdef HOST_BUILD_DIR
-  HOST_UNPACK := $(call UNPACK_CMD,$(HOST_BUILD_DIR)) $(call CRLF_CMD,$(HOST_BUILD_DIR))
+  HOST_UNPACK ?= $(call UNPACK_CMD,$(HOST_BUILD_DIR)) $(call CRLF_CMD,$(HOST_BUILD_DIR))
 endif
 
 endif # PKG_SOURCE