diff --git a/src/buffer/Buffer.zig b/src/buffer/Buffer.zig
index bcf1b4b..b05b3d4 100644
--- a/src/buffer/Buffer.zig
+++ b/src/buffer/Buffer.zig
@@ -989,7 +989,11 @@ const Node = union(enum) {
                         .case_folded => {
                             const input_consume_size = @min(ctx.buf.len - ctx.rest.len, input.len);
                             var writer = std.Io.Writer.fixed(ctx.buf[ctx.rest.len..]);
-                            const folded = unicode.case_folded_write_partial(&writer, input[0..input_consume_size]) catch return error.WriteFailed;
+                            var folded = unicode.case_folded_write_partial(&writer, input[0..input_consume_size]) catch return error.WriteFailed;
+                            if (folded.len == 0) {
+                                try writer.writeByte(input[0]);
+                                folded = input[0..1];
+                            }
                             ctx.rest = ctx.buf[0 .. ctx.rest.len + folded.len];
                             input = input[folded.len..];
                         },
diff --git a/src/buffer/unicode.zig b/src/buffer/unicode.zig
index db24595..4346f84 100644
--- a/src/buffer/unicode.zig
+++ b/src/buffer/unicode.zig
@@ -212,7 +212,7 @@ const Utf8PartialIterator = struct {
             return null;
         }
 
-        const cp_len = utf8ByteSequenceLength(it.bytes[it.end]) catch unreachable;
+        const cp_len = utf8ByteSequenceLength(it.bytes[it.end]) catch return null;
         if (it.end + cp_len > it.bytes.len) {
             return null;
         }