diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 162faf630..d7c822424 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -7,7 +7,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        go: ['1.12.17', '1.13.15', '1.14.10', '1.15.3']
+        go: ['1.13.15', '1.14.10', '1.15.3']
     name: Test with Go ${{ matrix.go }} on ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
     env:
diff --git a/go.mod b/go.mod
index 9acc3ac7a..babbbb29d 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/hajimehoshi/ebiten/v2
 
-go 1.12
+go 1.13
 
 require (
 	github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200707082815-5321531c36a2
diff --git a/goversion.go b/goversion.go
index edffd6472..42de102f6 100644
--- a/goversion.go
+++ b/goversion.go
@@ -12,12 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build go1.12
+// +build go1.13
 
 package ebiten
 
-// Ebiten forces to use Go 1.12 or later, since
+// Ebiten forces to use Go 1.13 or later, since
 // 1) Between Go 1.10 and Go 1.11, ioutil.TempFile's behavior is different. Ebiten forces the Go version in order to avoid confusion. (#777)
 // 2) FuncOf in syscall/js is defined as of Go 1.12.
+// 3) os.UserConfigDir is defined as of Go 1.13.
 
-const __EBITEN_REQUIRES_GO_VERSION_1_12_OR_LATER__ = true
+const __EBITEN_REQUIRES_GO_VERSION_1_13_OR_LATER__ = true
diff --git a/init.go b/init.go
index 4de656168..7f61ca8aa 100644
--- a/init.go
+++ b/init.go
@@ -18,7 +18,7 @@ import (
 	"github.com/hajimehoshi/ebiten/v2/internal/graphicscommand"
 )
 
-var _ = __EBITEN_REQUIRES_GO_VERSION_1_12_OR_LATER__
+var _ = __EBITEN_REQUIRES_GO_VERSION_1_13_OR_LATER__
 
 func init() {
 	graphicscommand.SetGraphicsDriver(uiDriver().Graphics())
diff --git a/internal/glfw/gen.go b/internal/glfw/gen.go
index 3d82973bb..42323a0e3 100644
--- a/internal/glfw/gen.go
+++ b/internal/glfw/gen.go
@@ -17,7 +17,11 @@
 package main
 
 import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
 	"fmt"
+	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -107,11 +111,10 @@ func run() error {
 			return err
 		}
 
-		in, err := os.Open(dll)
+		in, err := ioutil.ReadFile(dll)
 		if err != nil {
 			return err
 		}
-		defer in.Close()
 
 		out, err := os.Create(fmt.Sprintf("glfwdll_windows_%s.go", arch))
 		if err != nil {
@@ -120,10 +123,27 @@ func run() error {
 		defer out.Close()
 
 		// As the file name already specified the build environment, buildtags are not requried.
-		if err := file2byteslice.Write(out, in, true, "", "glfw", "glfwDLLCompressed"); err != nil {
+		if err := file2byteslice.Write(out, bytes.NewReader(in), true, "", "glfw", "glfwDLLCompressed"); err != nil {
 			return err
 		}
 
+		// Dump the hash
+		hashout, err := os.Create(fmt.Sprintf("glfwdllhash_windows_%s.go", arch))
+		if err != nil {
+			return err
+		}
+		defer hashout.Close()
+		hash := sha256.Sum256(in)
+		if _, err := fmt.Fprintf(hashout, `// Code generated by gen.go. DO NOT EDIT.
+
+package glfw
+
+const glfwDLLHash = "%s"
+`, hex.EncodeToString(hash[:])); err != nil {
+			return err
+		}
+
+		// Clean up the files.
 		for _, o := range objs {
 			if err := os.Remove(o); err != nil {
 				return err
diff --git a/internal/glfw/glfwdllhash_windows_386.go b/internal/glfw/glfwdllhash_windows_386.go
new file mode 100644
index 000000000..302ebfffe
--- /dev/null
+++ b/internal/glfw/glfwdllhash_windows_386.go
@@ -0,0 +1,5 @@
+// Code generated by gen.go. DO NOT EDIT.
+
+package glfw
+
+const glfwDLLHash = "93ce68219cb0e920a0b9f04a38bbeff104f530a643fd0a792215572525869f90"
diff --git a/internal/glfw/glfwdllhash_windows_amd64.go b/internal/glfw/glfwdllhash_windows_amd64.go
new file mode 100644
index 000000000..c3d3eaf0d
--- /dev/null
+++ b/internal/glfw/glfwdllhash_windows_amd64.go
@@ -0,0 +1,5 @@
+// Code generated by gen.go. DO NOT EDIT.
+
+package glfw
+
+const glfwDLLHash = "9297f0b5337eb17f170398f4e027f59a8daf502cb45cff9b74b615d70d8369c2"
diff --git a/internal/glfw/load_windows.go b/internal/glfw/load_windows.go
index 889afe064..35d2a6042 100644
--- a/internal/glfw/load_windows.go
+++ b/internal/glfw/load_windows.go
@@ -19,8 +19,8 @@ import (
 	"compress/gzip"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
+	"path/filepath"
 	"unsafe"
 
 	"golang.org/x/sys/windows"
@@ -28,7 +28,6 @@ import (
 
 type dll struct {
 	d     *windows.LazyDLL
-	path  string
 	procs map[string]*windows.LazyProc
 }
 
@@ -47,37 +46,45 @@ func (d *dll) call(name string, args ...uintptr) uintptr {
 	return r
 }
 
-func createTempDLL(content io.Reader) (string, error) {
-	f, err := ioutil.TempFile("", "glfw.*.dll")
-	if err != nil {
-		return "", err
-	}
-	defer f.Close()
-
-	fn := f.Name()
-
-	if _, err := io.Copy(f, content); err != nil {
-		return "", err
-	}
-
-	return fn, nil
-}
-
 func loadDLL() (*dll, error) {
-	f, err := gzip.NewReader(bytes.NewReader(glfwDLLCompressed))
+	cachedir, err := os.UserCacheDir()
 	if err != nil {
 		return nil, err
 	}
-	defer f.Close()
 
-	fn, err := createTempDLL(f)
-	if err != nil {
+	dir := filepath.Join(cachedir, "ebiten")
+	if err := os.MkdirAll(dir, 0755); err != nil {
 		return nil, err
 	}
 
+	fn := filepath.Join(dir, glfwDLLHash+".dll")
+	if _, err := os.Stat(fn); err != nil {
+		if !os.IsNotExist(err) {
+			return nil, err
+		}
+
+		f, err := gzip.NewReader(bytes.NewReader(glfwDLLCompressed))
+		if err != nil {
+			return nil, err
+		}
+		defer f.Close()
+
+		out, err := os.Create(fn)
+		if err != nil {
+			return nil, err
+		}
+		defer out.Close()
+
+		if _, err := io.Copy(out, f); err != nil {
+			return nil, err
+		}
+		if err := out.Sync(); err != nil {
+			return nil, err
+		}
+	}
+
 	return &dll{
-		d:    windows.NewLazyDLL(fn),
-		path: fn,
+		d: windows.NewLazyDLL(fn),
 	}, nil
 }
 
@@ -85,9 +92,6 @@ func (d *dll) unload() error {
 	if err := windows.FreeLibrary(windows.Handle(d.d.Handle())); err != nil {
 		return err
 	}
-	if err := os.Remove(d.path); err != nil {
-		return err
-	}
 	return nil
 }