diff --git a/source/blender/compositor/operations/COM_GlareBloomOperation.cc b/source/blender/compositor/operations/COM_GlareBloomOperation.cc
index 5540f6b0bc2..3b55b7b8da8 100644
--- a/source/blender/compositor/operations/COM_GlareBloomOperation.cc
+++ b/source/blender/compositor/operations/COM_GlareBloomOperation.cc
@@ -19,7 +19,7 @@
 
 namespace blender::compositor {
 
-void upsample(const MemoryBuffer &input, MemoryBuffer &output)
+static void upsample(const MemoryBuffer &input, MemoryBuffer &output)
 {
   const int2 output_size = int2(output.get_width(), output.get_height());