diff --git a/Makefile b/Makefile
index d5bce0a..f1ad383 100644
--- a/Makefile
+++ b/Makefile
@@ -26,7 +26,7 @@ install:
 	@mkdir -p $(MANDIR)/man1
 	@cp -f pb.1 $(MANDIR)/man1/pb.1
 	@chmod 644 $(MANDIR)/man1/pb.1
-ifdef CPLDIR
+ifeq ($(CPLDIR),)
 	@echo Installing the command completion to $(CPLDIR)
 	@mkdir -p $(CPLDIR)
 	@cp -f pb.d $(CPLDIR)/pb
@@ -38,7 +38,7 @@ uninstall:
 	@rm -f $(BINDIR)/pb
 	@echo Removing the manual page from $(MANDIR)/man1
 	@rm -f $(BINDIR)/man1/pb.1
-ifdef CPLDIR
+ifeq ($(CPLDIR),)
 	@echo Removing the command completion from $(CPLDIR)
 	@rm -f $(CPLDIR)/pb
 endif