diff --git a/Makefile b/Makefile
index 3dc8169cf..ca30b79e2 100644
--- a/Makefile
+++ b/Makefile
@@ -932,7 +932,7 @@ LTO_FLAGS           := $(OPTIMISATION_BASE) $(OPTIMISE_DEFAULT)
 
 else ifeq ($(TARGET),$(filter $(TARGET),$(F3_TARGETS)))
 OPTIMISE_DEFAULT    := -O2
-OPTIMISE_SPEED      := -O3
+OPTIMISE_SPEED      := -Ofast
 OPTIMISE_SIZE       := -Os
 
 LTO_FLAGS           := $(OPTIMISATION_BASE) $(OPTIMISE_SPEED)