diff --git a/go.mod b/go.mod
index b5ebd1f6b..cc3ab481a 100644
--- a/go.mod
+++ b/go.mod
@@ -1,5 +1,7 @@
 module github.com/hajimehoshi/ebiten
 
+go 1.12
+
 require (
 	github.com/go-gl/glfw v0.0.0-20181213070059-819e8ce5125f
 	github.com/gofrs/flock v0.7.0
diff --git a/goversion.go b/goversion.go
index a25f7565f..edffd6472 100644
--- a/goversion.go
+++ b/goversion.go
@@ -12,11 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// +build go1.11
+// +build go1.12
 
 package ebiten
 
-// 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)
+// Ebiten forces to use Go 1.12 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.
 
-const __EBITEN_REQUIRES_GO_VERSION_1_11_OR_LATER__ = true
+const __EBITEN_REQUIRES_GO_VERSION_1_12_OR_LATER__ = true
diff --git a/run.go b/run.go
index 75b29312f..54fc43206 100644
--- a/run.go
+++ b/run.go
@@ -23,7 +23,7 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/web"
 )
 
-var _ = __EBITEN_REQUIRES_GO_VERSION_1_11_OR_LATER__
+var _ = __EBITEN_REQUIRES_GO_VERSION_1_12_OR_LATER__
 
 // TPS represents a default ticks per second, that represents how many times game updating happens in a second.
 const DefaultTPS = 60