diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
index 30d74ae..cd84b02 100644
--- a/src/gallium/docs/source/tgsi.rst
+++ b/src/gallium/docs/source/tgsi.rst
@@ -442,7 +442,7 @@
 
   dst.z = \cos{src.x}
 
-  dst.w = \cos{src.w}
+  dst.w = \cos{src.x}
 
 
 DDX - Derivative Relative To X
@@ -552,7 +552,7 @@
 
   dst.z = \sin{src.x}
 
-  dst.w = \sin{src.w}
+  dst.w = \sin{src.x}
 
 
 SLE - Set On Less Equal Than