diff --git a/doc/optimization.txt b/doc/optimization.txt
index 06ad3ab880..c2e89a58a2 100644
--- a/doc/optimization.txt
+++ b/doc/optimization.txt
@@ -20,7 +20,7 @@ architecture-specific versions. It is recommended to look at older
 revisions of the interesting files (web frontends for the various FFmpeg
 branches are listed at http://ffmpeg.org/download.html).
 Alternatively, look into the other architecture-specific versions in
-the x86/, ppc/, alpha/ subdirectories. Even if you don't exactly
+the x86/, ppc/, aarch64/ subdirectories. Even if you don't exactly
 comprehend the instructions, it could help understanding the functions
 and how they can be optimized.