diff --git a/marshaller/Makefile b/marshaller/Makefile
index 3016412..f58633d 100644
--- a/marshaller/Makefile
+++ b/marshaller/Makefile
@@ -8,14 +8,17 @@ BIN_NAME = marshaller-gen
 $(BIN_NAME): src/codegen.c gen/lex.yy.c gen/y.tab.c
 	$(CC) -Isrc/ -o $@ $^
 
-gen/y.tab.c gen/y.tab.h: src/parser.y
+gen/y.tab.c gen/y.tab.h: src/parser.y gen
 	$(YACC) $(YFLAGS) $<
 	mv y.tab.c gen/
 	mv y.tab.h gen/
 
-gen/lex.yy.c: src/scanner.l gen/y.tab.h
+gen/lex.yy.c: src/scanner.l gen/y.tab.h gen
 	$(LEX) $<
 	mv lex.yy.c gen/
 
+gen:
+	mkdir -p gen/
+
 clean:
 	rm -f gen/* $(BIN_NAME)