diff --git a/similar/arch/ogl/gr.cpp b/similar/arch/ogl/gr.cpp
index 597ba2376..2bbc5ec5f 100644
--- a/similar/arch/ogl/gr.cpp
+++ b/similar/arch/ogl/gr.cpp
@@ -144,7 +144,7 @@ void ogl_swap_buffers_internal(void)
 #define ELEMENT_CHANGE_MASK_RESOURCE  (1<<4)
 #define ELEMENT_CHANGE_TRANSFORM      (1<<5)
 
-void rpi_destroy_element(void)
+static void rpi_destroy_element(void)
 {
 	if (dispman_element != DISPMANX_NO_HANDLE) {
 		DISPMANX_UPDATE_HANDLE_T dispman_update;
@@ -158,7 +158,7 @@ void rpi_destroy_element(void)
 	}
 }
 
-int rpi_setup_element(int x, int y, Uint32 video_flags, int update)
+static int rpi_setup_element(int x, int y, Uint32 video_flags, int update)
 {
 	// this code is based on the work of Ben O'Steen
 	// http://benosteen.wordpress.com/2012/04/27/using-opengl-es-2-0-on-the-raspberry-pi-without-x-windows/
@@ -269,7 +269,7 @@ int rpi_setup_element(int x, int y, Uint32 video_flags, int update)
 #endif // RPI
 
 #ifdef OGLES
-void ogles_destroy(void)
+static void ogles_destroy(void)
 {
 	if( eglDisplay != EGL_NO_DISPLAY ) {
 		eglMakeCurrent(eglDisplay, NULL, NULL, EGL_NO_CONTEXT);