diff --git a/make/subtree.mk b/make/subtree.mk
index 50ccd96c..ebb67441 100644
--- a/make/subtree.mk
+++ b/make/subtree.mk
@@ -19,8 +19,8 @@ endif
 #SUBTREE_SRC = $(shell find .)
 #endif
 
-SUBTREE_DIRS = $(shell for f in `git ls-files . || find | sed 's%/[^/]\+$$%%' | sort -u | grep -v Makefile`; do if [ -d "$$f" ]; then echo $$f; fi; done)
-SUBTREE_FILES = $(shell for f in `git ls-files . || find | grep -v Makefile`; do if [ -f "$$f" ]; then echo $$f; fi; done)
+SUBTREE_DIRS = $(shell for f in `git ls-files . 2>/dev/null || find | sed 's%/[^/]\+$$%%' | sort -u | grep -v Makefile`; do if [ -d "$$f" ]; then echo $$f; fi; done)
+SUBTREE_FILES = $(shell for f in `git ls-files . 2>/dev/null || find | grep -v Makefile`; do if [ -f "$$f" ]; then echo $$f; fi; done)
 
 INSTALLED_SUBTREE_DIRS = $(addprefix $(ENV_PREFIX)$(SUBTREE_INSTALL_PREFIX)/,$(SUBTREE_DIRS))
 INSTALLED_SUBTREE_FILES = $(addprefix $(ENV_PREFIX)$(SUBTREE_INSTALL_PREFIX)/,$(SUBTREE_FILES))