diff --git a/package/mmc-utils/mmc-utils.mk b/package/mmc-utils/mmc-utils.mk
index 286e73b242..8c264a454a 100644
--- a/package/mmc-utils/mmc-utils.mk
+++ b/package/mmc-utils/mmc-utils.mk
@@ -9,8 +9,12 @@ MMC_UTILS_SITE = git://git.kernel.org/pub/scm/linux/kernel/git/cjb/mmc-utils.git
 MMC_UTILS_LICENSE = GPL-2.0
 MMC_UTILS_LICENSE_FILES = mmc.h
 
+# override AM_CFLAGS as the project Makefile uses it to pass
+# -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2, and the latter conflicts
+# with the _FORTIFY_SOURCE that we pass when hardening options are
+# enabled.
 define MMC_UTILS_BUILD_CMDS
-	$(MAKE) -C $(@D) $(TARGET_CONFIGURE_OPTS)
+	$(MAKE) -C $(@D) $(TARGET_CONFIGURE_OPTS) AM_CFLAGS=
 endef
 
 define MMC_UTILS_INSTALL_TARGET_CMDS