diff --git a/makefiles/tools/uf2conv.inc.mk b/makefiles/tools/uf2conv.inc.mk
index c2a952e939..a000f71335 100644
--- a/makefiles/tools/uf2conv.inc.mk
+++ b/makefiles/tools/uf2conv.inc.mk
@@ -1,5 +1,11 @@
 FLASHFILE ?= $(HEXFILE)
 
+# Warn about deprecated variables
+ifneq (,$(FFLAGS_OPTS))
+  $(warning Warning! FFLAGS_OPTS is deprecated use UF2CONV_FLAGS)
+  UF2CONV_FLAGS ?= $(FFLAGS_OPTS)
+endif
+
 FLASHER ?= $(RIOTTOOLS)/uf2/uf2conv.py
 FFLAGS  ?= $(UF2CONV_FLAGS) $(FLASHFILE)