diff --git a/libc/spec/gnu_ext.td b/libc/spec/gnu_ext.td
index 161bb4e4a0d9d..e360c766c5c54 100644
--- a/libc/spec/gnu_ext.td
+++ b/libc/spec/gnu_ext.td
@@ -237,7 +237,11 @@ def GnuExtensions : StandardSpec<"GNUExtensions"> {
       [], // Types
       [], // Enumerations
       [
-        //TODO: Add getauxval here
+          FunctionSpec<
+              "getauxval",
+              RetValSpec<UnsignedLongType>,
+              [ArgSpec<UnsignedLongType>]
+          >,
       ]  // Functions
   >;