diff -rupN --no-dereference libwebp-1.2.1/CMakeLists.txt libwebp-1.2.1-new/CMakeLists.txt
--- libwebp-1.2.1/CMakeLists.txt	2021-07-30 00:55:37.000000000 +0200
+++ libwebp-1.2.1-new/CMakeLists.txt	2021-08-15 22:29:28.671542257 +0200
@@ -521,8 +521,8 @@ endif()
 
 if(WEBP_BUILD_VWEBP)
   # vwebp
-  find_package(GLUT)
-  if(GLUT_FOUND)
+  find_package(FreeGLUT)
+  if(FreeGLUT_FOUND)
     include_directories(${WEBP_DEP_IMG_INCLUDE_DIRS})
     parse_makefile_am(${CMAKE_CURRENT_SOURCE_DIR}/examples "VWEBP_SRCS" "vwebp")
     add_executable(vwebp ${VWEBP_SRCS})
diff -rupN --no-dereference libwebp-1.2.1/examples/vwebp.c libwebp-1.2.1-new/examples/vwebp.c
--- libwebp-1.2.1/examples/vwebp.c	2021-07-30 00:55:37.000000000 +0200
+++ libwebp-1.2.1-new/examples/vwebp.c	2021-08-15 22:29:28.671542257 +0200
@@ -27,7 +27,7 @@
 #if defined(HAVE_GLUT_GLUT_H)
 #include <GLUT/glut.h>
 #else
-#include <GL/glut.h>
+#include <GL/freeglut.h>
 #ifdef FREEGLUT
 #include <GL/freeglut.h>
 #endif