diff --git a/components/bt/component.mk b/components/bt/component.mk
index a9233cc74a..e88651aa13 100644
--- a/components/bt/component.mk
+++ b/components/bt/component.mk
@@ -4,8 +4,6 @@
 
 #COMPONENT_ADD_INCLUDEDIRS := 
 
-CURRENT_DIR=$(IDF_PATH)/components/bt
-
 COMPONENT_ADD_INCLUDEDIRS := include
 
 CFLAGS += -Wno-error=unused-label -Wno-error=return-type -Wno-error=missing-braces -Wno-error=pointer-sign -Wno-error=parentheses
@@ -22,4 +20,4 @@ ALL_LIB_FILES := $(patsubst %,$(COMPONENT_PATH)/lib/lib%.a,$(LIBS))
 $(COMPONENT_LIBRARY): $(ALL_LIB_FILES)
 
 # automatically trigger a git submodule update if BT library is missing
-$(eval $(call SubmoduleRequiredForFiles,$(ALL_LIB_FILES)))
+$(eval $(call SubmoduleCheck,$(ALL_LIB_FILES),$(COMPONENT_PATH)/lib))
diff --git a/components/esp32/component.mk b/components/esp32/component.mk
index 6eac77afd3..b41acee60d 100644
--- a/components/esp32/component.mk
+++ b/components/esp32/component.mk
@@ -27,7 +27,7 @@ ALL_LIB_FILES := $(patsubst %,$(COMPONENT_PATH)/lib/lib%.a,$(LIBS))
 
 # automatically trigger a git submodule update
 # if any libraries are missing
-$(eval $(call SubmoduleRequiredForFiles,$(ALL_LIB_FILES)))
+$(eval $(call SubmoduleCheck,$(ALL_LIB_FILES),$(COMPONENT_PATH)/lib))
 
 # this is a hack to make sure the app is re-linked if the binary
 # libraries change or are updated. If they change, the main esp32
diff --git a/components/esptool_py/Makefile.projbuild b/components/esptool_py/Makefile.projbuild
index a3d49b7df9..4d0dd1b3e5 100644
--- a/components/esptool_py/Makefile.projbuild
+++ b/components/esptool_py/Makefile.projbuild
@@ -31,4 +31,4 @@ app-flash: $(APP_BIN) $(ESPTOOLPY_SRC)
 	@echo "Flashing app to serial port $(ESPPORT), offset $(CONFIG_APP_OFFSET)..."
 	$(Q) $(ESPTOOLPY_WRITE_FLASH) $(CONFIG_APP_OFFSET) $(APP_BIN)
 
-$(eval $(call SubmoduleRequiredForFiles,$(ESPTOOLPY_SRC)))
+$(eval $(call SubmoduleCheck,$(ESPTOOLPY_SRC),$(COMPONENT_PATH)/esptool))
diff --git a/make/common.mk b/make/common.mk
index a515584a9b..14aa4074b3 100644
--- a/make/common.mk
+++ b/make/common.mk
@@ -23,19 +23,27 @@ summary := @echo
 details := @true
 endif
 
-# Pseudo-target to handle the case where submodules need to be
-# re-initialised.
+# Pseudo-target to check a git submodule has been properly initialised
 #
-# $(eval $(call SubmoduleRequiredForFiles,FILENAMES)) to create a target that
-# automatically runs 'git submodule update --init' if those files
-# are missing, and fails if this is not possible.
-define SubmoduleRequiredForFiles
+# $(eval $(call SubmoduleCheck,FILENAMES,SUBMODULE_PATH)) to create a target that
+# automatically runs 'git submodule update --init SUBMODULE_PATH' if any of
+# the files in FILENAMES are missing, and fails if this is not possible.
+#
+# Will also print a WARNING if the submodule at SUBMODULE_PATH appears
+# to require an update.
+define SubmoduleCheck
 $(1):
-	@echo "WARNING: Missing submodule for $$@..."
+	@echo "WARNING: Missing submodule $(2) for $$@..."
 	$(Q) [ -d ${IDF_PATH}/.git ] || ( echo "ERROR: esp-idf must be cloned from git to work."; exit 1)
 	$(Q) [ -x $(which git) ] || ( echo "ERROR: Need to run 'git submodule --init' in esp-idf root directory."; exit 1)
 	@echo "Attempting 'git submodule update --init' in esp-idf root directory..."
-	cd ${IDF_PATH} && git submodule update --init
+	cd ${IDF_PATH} && git submodule update --init $(2)
+
+# Parse 'git submodule status' output for out-of-date submodule.
+# Status output prefixes status line with '+' if the submodule commit doesn't match
+ifneq ("$(shell cd ${IDF_PATH} && git submodule status $(2) | grep '^+')","")
+$$(info WARNING: git submodule $2 may be out of date. Run 'git submodule update' to update.)
+endif
 endef