diff --git a/ext/glew/CMakeLists.txt b/ext/glew/CMakeLists.txt
index f147939a92..3b242d9ff4 100644
--- a/ext/glew/CMakeLists.txt
+++ b/ext/glew/CMakeLists.txt
@@ -1,5 +1,5 @@
 find_package(GLEW)
-if(NOT APPLE AND GLEW_FOUND)
+if((NOT APPLE OR USE_SYSTEM_FFMPEG) AND GLEW_FOUND)
   add_library(system_glew INTERFACE)
   add_library(Ext::GLEW ALIAS system_glew)
   target_link_libraries(system_glew INTERFACE GLEW::GLEW)