diff --git a/lib/std/Io/net.zig b/lib/std/Io/net.zig
index 787e3e8c8b475f0c6327440d1781da26e90336db..c32d7dfa5016d16ca6c79ba890c9372fec056c27 100644
--- a/lib/std/Io/net.zig
+++ b/lib/std/Io/net.zig
@@ -512,7 +512,7 @@ pub const Ip6Address = struct {
             // Has to be u16 elements to handle 3-digit hex numbers from compression.
             var parts: [8]u16 = @splat(0);
             var parts_i: u8 = 0;
-            var text_i: usize = 0;
+            var text_i: u8 = 0;
             var digit_i: u8 = 0;
             var compress_start: ?u8 = null;
             var interface_name_text: ?[]const u8 = null;
@@ -576,7 +576,7 @@ pub const Ip6Address = struct {
                         const name = text[text_i..];
                         if (name.len == 0) return .incomplete;
                         interface_name_text = name;
-                        text_i = text.len;
+                        text_i = std.math.cast(u8, text.len) orelse return .{ .overflow = text.len };
                         continue :state .end;
                     },
                     else => return .{ .invalid_byte = text_i },
diff --git a/lib/std/Io/net/test.zig b/lib/std/Io/net/test.zig
index ddf6a9866c486d550caca51242f4d1f8f692fc11..308dc1a32670e207e72511d0128b634972050e6a 100644
--- a/lib/std/Io/net/test.zig
+++ b/lib/std/Io/net/test.zig
@@ -94,7 +94,7 @@ test "invalid but parseable IPv6 scope ids" {
 
 test "oversized IPv6 scope id" {
     const long_scope: [256]u8 = @splat('a');
-    try testing.expectError(error.NameTooLong, net.IpAddress.resolveIp6(testing.io, "ff01::fb%" ++ &long_scope, 0));
+    try testing.expectError(error.ParseFailed, net.IpAddress.resolveIp6(testing.io, "ff01::fb%" ++ &long_scope, 0));
 }
 
 test "parse and render IPv4 addresses" {