Us go build instead of go install.

Go install places the binaries wherever the GOPATH is set which could be
some non related directory. Rather use go build and place the binaries in
this directory.

Makefile

@@ -28,11 +28,11 @@
 
 .PHONY: test install gofmt
 
-install:
+build:
-	go install ./cmd/invertergui/
+	go build ./cmd/invertergui/
-	go install ./cmd/invertercli/
+	go build ./cmd/invertercli/
 
-all: install gofmt test
+all: build gofmt test
 
 gofmt:
 	gofmt -l -s -w .