diff --git a/include/osg/GL2Extensions b/include/osg/GL2Extensions
index 2c59feee0..39d2c3545 100644
--- a/include/osg/GL2Extensions
+++ b/include/osg/GL2Extensions
@@ -194,8 +194,8 @@ typedef char GLchar;
 #define GL_PROGRAM_POINT_SIZE_EXT                    0x8642
 #endif
 
-// ARB_tesselation_shader
-#ifndef GL_ARB_tesselation_shader
+// ARB_tessellation_shader
+#ifndef GL_ARB_tessellation_shader
 #define GL_PATCHES                                             0x000E
 #define GL_PATCH_VERTICES                                      0x8E72
 #define GL_PATCH_DEFAULT_INNER_LEVEL                           0x8E73