diff --git a/vendor/clouds3d.js b/vendor/clouds3d.js
index 0f62a5b..9dfa02e 100644
--- a/vendor/clouds3d.js
+++ b/vendor/clouds3d.js
@@ -92,6 +92,7 @@ var FRAG_SRC = [
     'uniform float uAtmoDensity;',
     'uniform float uAtmoGrayTau;',
     'uniform float uAtmoGain;',
+    'uniform float uEarthRadius;',
     'uniform vec3 uAtmoBlueColor;',
     'uniform vec3 uAtmoGrayColor;',
     'uniform vec3 uSunColor;',     // direct beam after atmospheric extinction