diff --git a/Makefile b/Makefile
index 1643b74..8f1ae11 100644
--- a/Makefile
+++ b/Makefile
@@ -33,7 +33,7 @@ c++decl: cdgram.c cdlex.c cdecl.c
 	rm -f cdecl
 
 cdlex.c: cdlex.l
-	lex cdlex.l && mv lex.yy.c cdlex.c
+	flex cdlex.l && mv lex.yy.c cdlex.c
 
 cdgram.c: cdgram.y
 	yacc cdgram.y && mv y.tab.c cdgram.c