diff --git a/internal/graphics/opengl/context_desktop.go b/internal/graphics/opengl/context_desktop.go
index c5167bca6..74281c6fd 100644
--- a/internal/graphics/opengl/context_desktop.go
+++ b/internal/graphics/opengl/context_desktop.go
@@ -40,10 +40,10 @@ func (p Program) Equals(other Program) bool {
 type UniformLocation int32
 type AttribLocation int32
 
-type ProgramID uint32
+type programID uint32
 
-func (p Program) ID() ProgramID {
-	return ProgramID(p)
+func (p Program) id() programID {
+	return programID(p)
 }
 
 type context struct {
diff --git a/internal/graphics/opengl/context_js.go b/internal/graphics/opengl/context_js.go
index f0e04f4d1..a40a98ebe 100644
--- a/internal/graphics/opengl/context_js.go
+++ b/internal/graphics/opengl/context_js.go
@@ -56,10 +56,10 @@ type UniformLocation struct {
 
 type AttribLocation int
 
-type ProgramID int
+type programID int
 
-func (p Program) ID() ProgramID {
-	return ProgramID(p.Get("__ebiten_programId").Int())
+func (p Program) id() programID {
+	return programID(p.Get("__ebiten_programId").Int())
 }
 
 type context struct {
@@ -264,7 +264,7 @@ func (c *Context) GlslHighpSupported() bool {
 	return gl.Call("getShaderPrecisionFormat", gl.FRAGMENT_SHADER, gl.HIGH_FLOAT).Get("precision").Int() != 0
 }
 
-var lastProgramID ProgramID = 0
+var lastProgramID programID = 0
 
 func (c *Context) NewProgram(shaders []Shader) (Program, error) {
 	gl := c.gl
diff --git a/internal/graphics/opengl/context_mobile.go b/internal/graphics/opengl/context_mobile.go
index 044e08566..0d1dedfe0 100644
--- a/internal/graphics/opengl/context_mobile.go
+++ b/internal/graphics/opengl/context_mobile.go
@@ -41,10 +41,10 @@ func (p Program) Equals(other Program) bool {
 type UniformLocation mgl.Uniform
 type AttribLocation mgl.Attrib
 
-type ProgramID uint32
+type programID uint32
 
-func (p Program) ID() ProgramID {
-	return ProgramID(p.Value)
+func (p Program) id() programID {
+	return programID(p.Value)
 }
 
 type context struct {
diff --git a/internal/graphics/opengl/locationcache.go b/internal/graphics/opengl/locationcache.go
index 8213f06a3..884090617 100644
--- a/internal/graphics/opengl/locationcache.go
+++ b/internal/graphics/opengl/locationcache.go
@@ -14,10 +14,10 @@
 
 package opengl
 
-// Since js.Object (Program) can't be keys of a map, use integers (ProgramID) instead.
+// Since js.Object (Program) can't be keys of a map, use integers (programID) instead.
 
-var uniformLocationCache = map[ProgramID]map[string]UniformLocation{}
-var attribLocationCache = map[ProgramID]map[string]AttribLocation{}
+var uniformLocationCache = map[programID]map[string]UniformLocation{}
+var attribLocationCache = map[programID]map[string]AttribLocation{}
 
 type UniformLocationGetter interface {
 	getUniformLocation(p Program, location string) UniformLocation
@@ -26,7 +26,7 @@ type UniformLocationGetter interface {
 // TODO: Rename these functions not to be confusing
 
 func GetUniformLocation(g UniformLocationGetter, p Program, location string) UniformLocation {
-	id := p.ID()
+	id := p.id()
 	if _, ok := uniformLocationCache[id]; !ok {
 		uniformLocationCache[id] = map[string]UniformLocation{}
 	}
@@ -43,7 +43,7 @@ type AttribLocationGetter interface {
 }
 
 func GetAttribLocation(g AttribLocationGetter, p Program, location string) AttribLocation {
-	id := p.ID()
+	id := p.id()
 	if _, ok := attribLocationCache[id]; !ok {
 		attribLocationCache[id] = map[string]AttribLocation{}
 	}