diff --git a/Makefile b/Makefile
index 4b0896c..d29a5f6 100644
--- a/Makefile
+++ b/Makefile
@@ -6,27 +6,29 @@ CROSSPREFIX=x86_64-w64-mingw32
 CROSSCC = $(CROSSPREFIX)-gcc
 CROSSCXX = $(CROSSPREFIX)-g++
 GOBIN ?= go
+GOMODTIDY ?= $(GOBIN) mod tidy
+MFLAGS = -C $(SRC) GOBIN="$(GOBIN)" GOMODTIDY="$(GOMODTIDY)"
 
 .PHONY: all test clean
 
 all:
-	$(MAKE) -C $(SRC) GOBIN=$(GOBIN) unix
+	$(MAKE) $(MFLAGS) unix
 	$(MAKE) dist
 
 headless:
-	$(MAKE) -C $(SRC) GOBIN=$(GOBIN) unix-headless
+	$(MAKE) $(MFLAGS) unix-headless
 	$(MAKE) dist
 
 win64:
-	$(MAKE) -C $(SRC) GOBIN=$(GOBIN) win64
+	$(MAKE) $(MFLAGS) win64
 	$(MAKE) dist
 
 win64-cross:
-	$(MAKE) -C $(SRC) GOBIN=$(GOBIN) CGO_ENABLED=1 CC=$(CROSSCC) CXX=$(CROSSCXX) win64
+	$(MAKE) $(MFLAGS) CGO_ENABLED=1 CC=$(CROSSCC) CXX=$(CROSSCXX) win64
 	$(MAKE) dist
 
 win64-headless:
-	$(MAKE) -C $(SRC) GOBIN=$(GOBIN) win64-headless
+	$(MAKE) $(MFLAGS) win64-headless
 	$(MAKE) dist
 
 dist:
diff --git a/src/Makefile b/src/Makefile
index 70227d8..1a2d0e3 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,25 +1,26 @@
 GOBIN ?= go
-LDFLAGS = -s -w
-LDFLAGS_WIN = -H windowsgui -s -w
-GOFLAGS = -trimpath
+GOMODTIDY ?= $(GOBIN) mod tidy
+LDFLAGS ?= -s -w
+LDFLAGS_WIN ?= -H windowsgui -s -w
+GOFLAGS ?= -trimpath
 SOURCES = server.go twitch.go youtube.go owncast.go kick.go
 SOURCES_GUI = $(SOURCES) gui.go
 BIN = streamgoose
 
 unix:
-	$(GOBIN) mod tidy
+	$(GOMODTIDY)
 	$(GOBIN) build $(GOFLAGS) -ldflags "$(LDFLAGS)" -o $(BIN) $(SOURCES_GUI)
 
 unix-headless:
-	$(GOBIN) mod tidy
+	$(GOMODTIDY)
 	$(GOBIN) build $(GOFLAGS) -ldflags "$(LDFLAGS)" -o $(BIN) $(SOURCES)
 
 win64:
-	$(GOBIN) mod tidy
+	$(GOMODTIDY)
 	GOOS=windows GOARCH=amd64 $(GOBIN) build $(GOFLAGS) -ldflags "$(LDFLAGS_WIN)" -o $(BIN).exe $(SOURCES_GUI)
 
 win64-headless:
-	$(GOBIN) mod tidy
+	$(GOMODTIDY)
 	GOOS=windows GOARCH=amd64 $(GOBIN) build $(GOFLAGS) -ldflags "$(LDFLAGS)" -o $(BIN).exe $(SOURCES)
 
 clean:
diff --git a/src/gui.go b/src/gui.go
index 4aba129..f067ca6 100644
--- a/src/gui.go
+++ b/src/gui.go
@@ -1,3 +1,4 @@
+// build +gui
 /*
   StreamGoose UI — Go reference implementation