diff --git a/core/Makefile b/core/Makefile
index 68f8677..5ddc015 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -545,11 +545,38 @@
 # Targets for user images
 # #################################################################
 
+INTERNAL_USERIMAGES_EXT_VARIANT :=
 ifeq ($(TARGET_USERIMAGES_USE_EXT2),true)
-include external/genext2fs/Config.mk
-INTERNAL_MKUSERFS := $(MKEXT2IMG)
+INTERNAL_USERIMAGES_USE_EXT := true
+INTERNAL_USERIMAGES_EXT_VARIANT := ext2
 else
-INTERNAL_MKUSERFS := $(MKYAFFS2)
+ifeq ($(TARGET_USERIMAGES_USE_EXT3),true)
+INTERNAL_USERIMAGES_USE_EXT := true
+INTERNAL_USERIMAGES_EXT_VARIANT := ext3
+else
+ifeq ($(TARGET_USERIMAGES_USE_EXT4),true)
+INTERNAL_USERIMAGES_USE_EXT := true
+INTERNAL_USERIMAGES_EXT_VARIANT := ext4
+endif
+endif
+endif
+
+ifeq ($(INTERNAL_USERIMAGES_USE_EXT),true)
+INTERNAL_USERIMAGES_DEPS := $(MKEXT2USERIMG) $(MAKE_EXT4FS)
+INTERNAL_USERIMAGES_BINARY_PATHS := $(sort $(dir $(INTERNAL_USERIMAGES_DEPS)))
+
+# $(1): src directory
+# $(2): output file
+# $(3): label
+# $(4): ext variant (ext2, ext3, ext4)
+# $(5): size of the partition
+define build-userimage-ext-target
+  @mkdir -p $(dir $(2))
+    $(hide) PATH=$(foreach p,$(INTERNAL_USERIMAGES_BINARY_PATHS),$(p):)$(PATH) \
+	  $(MKEXT2USERIMG) $(1) $(2) $(4) $(3) $(5)
+endef
+else
+INTERNAL_USERIMAGES_DEPS := $(MKYAFFS2)
 endif
 
 # -----------------------------------------------------------------
@@ -664,15 +691,15 @@
 	$(ALL_GENERATED_SOURCES) \
 	$(ALL_DEFAULT_INSTALLED_MODULES))
 
-ifeq ($(TARGET_USERIMAGES_USE_EXT2),true)
+ifeq ($(INTERNAL_USERIMAGES_USE_EXT),true)
 ## generate an ext2 image
 # $(1): output file
 define build-systemimage-target
     @echo "Target system fs image: $(1)"
-    $(call build-userimage-ext2-target,$(TARGET_OUT),$(1),system,)
+    $(call build-userimage-ext-target,$(TARGET_OUT),$(1),system,$(INTERNAL_USERIMAGES_EXT_VARIANT),$(BOARD_SYSTEMIMAGE_PARTITION_SIZE))
 endef
 
-else # TARGET_USERIMAGES_USE_EXT2 != true
+else # INTERNAL_USERIMAGES_USE_EXT != true
 
 ## generate a yaffs2 image
 # $(1): output file
@@ -681,9 +708,9 @@
     @mkdir -p $(dir $(1))
     $(hide) $(MKYAFFS2) -f $(mkyaffs2_extra_flags) $(TARGET_OUT) $(1)
 endef
-endif # TARGET_USERIMAGES_USE_EXT2
+endif # INTERNAL_USERIMAGES_USE_EXT
 
-$(BUILT_SYSTEMIMAGE_UNOPT): $(INTERNAL_SYSTEMIMAGE_FILES) $(INTERNAL_MKUSERFS)
+$(BUILT_SYSTEMIMAGE_UNOPT): $(INTERNAL_SYSTEMIMAGE_FILES) $(INTERNAL_USERIMAGES_DEPS)
 	$(call build-systemimage-target,$@)
 
 # The installed image, which may be optimized or unoptimized.
@@ -730,7 +757,7 @@
 
 .PHONY: systemimage-nodeps snod
 systemimage-nodeps snod: $(filter-out systemimage-nodeps snod,$(MAKECMDGOALS)) \
-	            | $(INTERNAL_MKUSERFS)
+	            | $(INTERNAL_USERIMAGES_DEPS)
 	@echo "make $@: ignoring dependencies"
 	$(call build-systemimage-target,$(INSTALLED_SYSTEMIMAGE))
 	$(hide) $(call assert-max-image-size,$(INSTALLED_SYSTEMIMAGE),$(BOARD_SYSTEMIMAGE_PARTITION_SIZE),yaffs)
@@ -764,16 +791,16 @@
 INTERNAL_USERDATAIMAGE_FILES := \
 	$(filter $(TARGET_OUT_DATA)/%,$(ALL_DEFAULT_INSTALLED_MODULES))
 
-ifeq ($(TARGET_USERIMAGES_USE_EXT2),true)
-## Generate an ext2 image
+ifeq ($(INTERNAL_USERIMAGES_USE_EXT),true)
+## Generate an ext image
 define build-userdataimage-target
     $(call pretty,"Target userdata fs image: $(INSTALLED_USERDATAIMAGE_TARGET)")
     @mkdir -p $(TARGET_OUT_DATA)
-    $(call build-userimage-ext2-target,$(TARGET_OUT_DATA),$(INSTALLED_USERDATAIMAGE_TARGET),userdata,)
+    $(call build-userimage-ext-target,$(TARGET_OUT_DATA),$(INSTALLED_USERDATAIMAGE_TARGET),userdata,$(INTERNAL_USERIMAGES_EXT_VARIANT),$(BOARD_USERDATAIMAGE_PARTITION_SIZE))
     $(hide) $(call assert-max-image-size,$(INSTALLED_USERDATAIMAGE_TARGET),$(BOARD_USERDATAIMAGE_PARTITION_SIZE),yaffs)
 endef
 
-else # TARGET_USERIMAGES_USE_EXT2 != true
+else # INTERNAL_USERIMAGES_USE_EXT != true
 
 ## Generate a yaffs2 image
 define build-userdataimage-target
@@ -782,18 +809,18 @@
     $(hide) $(MKYAFFS2) -f $(mkyaffs2_extra_flags) $(TARGET_OUT_DATA) $(INSTALLED_USERDATAIMAGE_TARGET)
     $(hide) $(call assert-max-image-size,$(INSTALLED_USERDATAIMAGE_TARGET),$(BOARD_USERDATAIMAGE_PARTITION_SIZE),yaffs)
 endef
-endif # TARGET_USERIMAGES_USE_EXT2
+endif # INTERNAL_USERIMAGES_USE_EXT
 
 BUILT_USERDATAIMAGE_TARGET := $(PRODUCT_OUT)/userdata.img
 
 # We just build this directly to the install location.
 INSTALLED_USERDATAIMAGE_TARGET := $(BUILT_USERDATAIMAGE_TARGET)
-$(INSTALLED_USERDATAIMAGE_TARGET): $(INTERNAL_MKUSERFS) \
+$(INSTALLED_USERDATAIMAGE_TARGET): $(INTERNAL_USERIMAGES_DEPS) \
                                    $(INTERNAL_USERDATAIMAGE_FILES)
 	$(build-userdataimage-target)
 
 .PHONY: userdataimage-nodeps
-userdataimage-nodeps: $(INTERNAL_MKUSERFS)
+userdataimage-nodeps: $(INTERNAL_USERIMAGES_DEPS)
 	$(build-userdataimage-target)
 
 #######
@@ -1142,6 +1169,7 @@
 	$(hide) ./build/tools/releasetools/img_from_target_files \
 	   -s $(extensions) \
 	   -p $(HOST_OUT) \
+	   $(addprefix --fs_type ,$(INTERNAL_USERIMAGES_EXT_VARIANT)) \
 	   $(BUILT_TARGET_FILES_PACKAGE) $@
 
 .PHONY: updatepackage
diff --git a/core/config.mk b/core/config.mk
index 81842be..897af83 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -206,6 +206,8 @@
 APICHECK := $(HOST_OUT_EXECUTABLES)/apicheck$(HOST_EXECUTABLE_SUFFIX)
 FS_GET_STATS := $(HOST_OUT_EXECUTABLES)/fs_get_stats$(HOST_EXECUTABLE_SUFFIX)
 MKEXT2IMG := $(HOST_OUT_EXECUTABLES)/genext2fs$(HOST_EXECUTABLE_SUFFIX)
+MAKE_EXT4FS := $(HOST_OUT_EXECUTABLES)/make_ext4fs$(HOST_EXECUTABLE_SUFFIX)
+MKEXT2USERIMG := $(HOST_OUT_EXECUTABLES)/mkuserimg.sh
 MKEXT2BOOTIMG := external/genext2fs/mkbootimg_ext2.sh
 MKTARBALL := build/tools/mktarball.sh
 TUNE2FS := tune2fs