diff --git a/http.zig b/http.zig
index b8b537de42ad2d36cea384cbf9e2d5e5297323f5..6d59dff291c9b8c7135f691d0685f567b34cdbb6 100644
--- a/http.zig
+++ b/http.zig
@@ -317,6 +317,7 @@ pub const HeadersMap = struct {
     fn findIndex(map: *const HeadersMap, n: []const u8) ?usize {
         for (n) |c| switch (c) {
             'a'...'z', '-' => {},
+            '0'...'9' => {},
             else => unreachable,
         };
         for (0..map.count()) |i| {