diff --git a/extern/gflags/CMakeLists.txt b/extern/gflags/CMakeLists.txt
index 82455c52e55..4f2fce3778b 100644
--- a/extern/gflags/CMakeLists.txt
+++ b/extern/gflags/CMakeLists.txt
@@ -1,6 +1,13 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 # Copyright 2016 Blender Foundation. All rights reserved.
 
+# Too noisy for code we don't maintain.
+if(CMAKE_COMPILER_IS_GNUCC)
+  if(NOT "${CMAKE_CXX_COMPILER_VERSION}" VERSION_LESS "8.0")
+    add_cxx_flag("-Wno-cast-function-type")
+  endif()
+endif()
+
 set(INC
   src
   src/gflags