diff --git a/Makefile b/Makefile
index 9bc1430..38e79e7 100644
--- a/Makefile
+++ b/Makefile
@@ -107,6 +107,7 @@ OPTIMIZE = -Os -ffunction-sections -finline-functions-called-once -mcall-prologu
 # OPTIMIZE = -O0
 CFLAGS = -g -Wall -Wstrict-prototypes $(OPTIMIZE) -mmcu=$(MCU_TARGET) $(DEFS) -std=gnu99 -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -save-temps
 LDFLAGS = -Wl,--as-needed -Wl,--gc-sections
+LIBS = -lm
 
 OBJ = $(patsubst %.c,%.o,${SOURCES})