diff --git a/lib/std/crypto.zig b/lib/std/crypto.zig
index 38a825654d006f920c9e11581fbd6e12b3d7d354..1a839f0c94ee24ea58f6e2a521f57649dba1bf59 100644
--- a/lib/std/crypto.zig
+++ b/lib/std/crypto.zig
@@ -302,6 +302,7 @@ test {
     _ = core.aes;
     _ = core.keccak;
     _ = core.Ascon;
+    _ = core.keccak;
     _ = core.modes;
 
     _ = dh.X25519;
diff --git a/lib/std/crypto/keccak_p.zig b/lib/std/crypto/keccak_p.zig
index 9164ba48bab7b6776ac8a4ab7f79d28b492c8120..fdcb993c96edf161e8c42580cd5545611451689b 100644
--- a/lib/std/crypto/keccak_p.zig
+++ b/lib/std/crypto/keccak_p.zig
@@ -78,7 +78,7 @@ pub fn KeccakF(comptime f: u11) type {
 
         /// XOR a byte into the state at a given offset.
         pub fn addByte(self: *Self, byte: u8, offset: usize) void {
-            const z = @sizeOf(T) * @as(math.Log2Int(T), @truncate(offset % @sizeOf(T)));
+            const z: math.Log2Int(T) = @intCast(8 * (offset % @sizeOf(T)));
             self.st[offset / @sizeOf(T)] ^= @as(T, byte) << z;
         }
 
@@ -382,6 +382,21 @@ test "Keccak-f800" {
     try std.testing.expectEqualSlices(u32, &st.st, &expected);
 }
 
+test "addByte" {
+    inline for (.{ 200, 400, 800, 1600 }) |f| {
+        const F = KeccakF(f);
+        for (0..F.block_bytes) |offset| {
+            var a: F = .{};
+            a.addByte(0xa5, offset);
+            var bytes: [F.block_bytes]u8 = @splat(0);
+            bytes[offset] = 0xa5;
+            var b: F = .{};
+            b.addBytes(&bytes);
+            try std.testing.expectEqual(b.st, a.st);
+        }
+    }
+}
+
 test "squeeze" {
     var st: State(800, 256, 22) = .init(@splat(0x80), 0x01);