diff --git a/src/Magnum/TextureTools/DistanceFieldShader.frag b/src/Magnum/TextureTools/DistanceFieldShader.frag
index b82c6d94b..1224b7f72 100644
--- a/src/Magnum/TextureTools/DistanceFieldShader.frag
+++ b/src/Magnum/TextureTools/DistanceFieldShader.frag
@@ -26,10 +26,13 @@
 #ifndef NEW_GLSL
 #define in varying
 #define value gl_FragColor.x
-#define const
 #define texture texture2D
 #endif
 
+#ifndef RUNTIME_CONST
+#define const
+#endif
+
 #if (defined(GL_ES) && __VERSION__ >= 300) || (!defined(GL_ES) && __VERSION__ >= 150)
 #define TEXELFETCH_USABLE
 #endif