diff --git a/Makefile b/Makefile
index 942da39..263c781 100644
--- a/Makefile
+++ b/Makefile
@@ -9,4 +9,4 @@ endif
 calculator : $(REQ)
 	bison -d $(SRC)/parser.y
 	flex -o calculator.lex.c $(SRC)/lexer.l
-	$(CC) $(CFLAGS) parser.tab.c calculator.lex.c $(SRC)/calculator.c $(SRC)/colour.c -o $@
\ No newline at end of file
+	$(CC) $(CFLAGS) parser.tab.c calculator.lex.c $(SRC)/calculator.c $(SRC)/colour.c -o $@ -lm
\ No newline at end of file