diff --git a/make/git-submod.mk b/make/git-submod.mk
index 7fabaf61..19499676 100644
--- a/make/git-submod.mk
+++ b/make/git-submod.mk
@@ -14,7 +14,7 @@ SUBMOD_PATH                  = $(patsubst $(abspath $(TOPDIR))/%,%,$(abspath $(C
 SUBMOD_SRC_DIR              ?= .
 SUB_GIT                      = git -C $(SUBMOD_SRC_DIR)
 SUBMOD_PKG_NAME             := $(shell $(SUB_GIT) remote -v | sed -n 's/^[a-zA-Z_]\+\s//; s/  *.*//; s%.*/%%; s%\.git%%; 1p')
-SUBMOD_MAIN_BRANCH          := $(shell $(SUB_GIT) branch --format '%(refname:lstrip=2)')
+SUBMOD_MAIN_BRANCH          := $(firstword $(shell $(SUB_GIT) branch --format '%(refname:lstrip=2)'))
 
 include $(MODDIR)/make/defs.mk