diff --git a/src/SCRIPTS/BF/ui.lua b/src/SCRIPTS/BF/ui.lua
index 97a2c74..42db07f 100644
--- a/src/SCRIPTS/BF/ui.lua
+++ b/src/SCRIPTS/BF/ui.lua
@@ -121,6 +121,10 @@ local function processMspReply(cmd,rx_buf)
                         raw_val = bit32.lshift(raw_val, (idx-1)*8)
                         f.value = bit32.bor(f.value, raw_val)
                     end
+                    local bits = #f.vals * 8
+                    if f.min < 0 and bit32.btest(f.value, bit32.lshift(1, bits - 1)) then
+                        f.value = f.value - (2 ^ bits)
+                    end
                     f.value = f.value/(f.scale or 1)
                 end
             end