diff --git a/src/panfrost/bifrost/valhall/ISA.xml b/src/panfrost/bifrost/valhall/ISA.xml
index bac6a0af035..b39137a917d 100644
--- a/src/panfrost/bifrost/valhall/ISA.xml
+++ b/src/panfrost/bifrost/valhall/ISA.xml
@@ -2061,7 +2061,7 @@
       as the `mux` modifier is evaluated on the mask. If true, `A` is chosen,
       else `B` is chosen. The `bit` modifier acts bitwise, equivalent to
       `bitselect()` in OpenCL, so `MUX.i32.bit A, B, mask` calculates
-      `(A & mask) | (A & ~mask)`.
+      `(A & mask) | (B & ~mask)`.
     </desc>
     <mod name="mux" start="32" size="2"/>
     <src>A</src>
@@ -2075,7 +2075,7 @@
       as the `mux` modifier is evaluated on the mask. If true, `A` is chosen,
       else `B` is chosen. The `bit` modifier acts bitwise, equivalent to
       `bitselect()` in OpenCL, so `MUX.i32.bit A, B, mask` calculates
-      `(A &amp; mask) | (A &amp; ~mask)`.
+      `(A &amp; mask) | (B &amp; ~mask)`.
     </desc>
     <mod name="mux" start="32" size="2"/>
     <src swizzle="true">A</src>