diff --git a/Makefile b/Makefile
index 43d3e3f..13a2ce6 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
-SOURCES = $(shell find . -name '*.go')
-PARSERS = $(shell find . -name '*.treerack')
+sources = $(shell find . -name '*.go')
+parsers = $(shell find . -name '*.treerack')
 
 .PHONY: cpu.out
 
@@ -9,18 +9,18 @@ deps:
 	go get golang.org/x/tools/cmd/goimports
 	go get -t ./...
 
-imports: $(SOURCES)
+imports: $(sources)
 	@echo imports
-	@goimports -w $(SOURCES)
+	@goimports -w $(sources)
 
-build: $(SOURCES)
+build: $(sources)
 	go build
 	go build -o cmd/treerack/treerack ./cmd/treerack
 
-install: $(SOURCES)
+install: $(sources)
 	go install ./cmd/treerack
 
-head: $(SOURCES) fmt
+head: $(sources) fmt
 	go run scripts/createhead.go -- \
 		char.go \
 		sequence.go \
@@ -44,12 +44,12 @@ head: $(SOURCES) fmt
 	> headexported.go
 	@gofmt -s -w headexported.go
 
-generate: $(SOURCES) $(PARSERS) fmt head install
+generate: $(sources) $(parsers) fmt head install
 	treerack generate -export -package-name self < syntax.treerack > self/self.go.next
 	@mv self/self.go.next self/self.go
 	@gofmt -s -w self/self.go
 
-regenerate: $(SOURCES) $(PARSERS) fmt head install
+regenerate: $(sources) $(parsers) fmt head install
 	treerack generate -export -package-name self < syntax.treerack > self/self.go.next
 	@mv self/self.go.next self/self.go
 	go install ./cmd/treerack
@@ -57,7 +57,7 @@ regenerate: $(SOURCES) $(PARSERS) fmt head install
 	@mv self/self.go.next self/self.go
 	@gofmt -s -w self/self.go
 
-check-generate: $(SOURCES) $(PARSERS)
+check-generate: $(sources) $(parsers)
 	@echo checking head
 	@mv headexported.go headexported.go.backup
 	@go run scripts/createhead.go --exported -- \
@@ -91,15 +91,15 @@ check-generate: $(SOURCES) $(PARSERS)
 	@mv headexported.go.backup headexported.go
 	@mv self/self.go.backup self/self.go
 
-check: build $(PARSERS)
+check: build $(parsers)
 	go test -test.short -run ^Test
 	go test ./cmd/treerack -test.short -run ^Test
 
-checkall: build $(PARSERS)
+checkall: build $(parsers)
 	go test
 	go test ./cmd/treerack
 
-.coverprofile: $(SOURCES)
+.coverprofile: $(sources)
 	go test -coverprofile .coverprofile
 
 cover: .coverprofile
@@ -108,7 +108,7 @@ cover: .coverprofile
 showcover: .coverprofile
 	go tool cover -html .coverprofile
 
-.coverprofile-cmd: $(SOURCES)
+.coverprofile-cmd: $(sources)
 	go test ./cmd/treerack -coverprofile .coverprofile-cmd
 
 cover-cmd: .coverprofile-cmd
@@ -128,11 +128,11 @@ cpu.out:
 cpu: cpu.out
 	go tool pprof -top cpu.out
 
-fmt: $(SOURCES)
-	gofmt -w -s $(SOURCES)
+fmt: $(sources)
+	gofmt -w -s $(sources)
 
-checkfmt: $(SOURCES)
-	if [ "$$(gofmt -s -d $(SOURCES))" != "" ]; then false; else true; fi
+checkfmt: $(sources)
+	if [ "$$(gofmt -s -d $(sources))" != "" ]; then false; else true; fi
 
 vet:
 	go vet ./...