diff --git a/README.md b/README.md
index b7f2d95..ef6e0fc 100644
--- a/README.md
+++ b/README.md
@@ -1612,7 +1612,7 @@ installed.
   it cannot go faster than 1 frame per millisecond, so 1000 is the fastest.
   (default: 1.0)
 - __optimization__ - `mem` or `cpu`. if optimizing for memory, animation frames
-  will be rendered to bitmaps _as the animation plays_, using less cpu.
+  will be rendered to bitmaps _as the animation plays_, using less memory.
   optimizing for cpu will precompile all bitmaps beforehand, which may be
   faster, but might also OOM the process on large images. (default: `mem`).