diff --git a/libscan/util.h b/libscan/util.h
index fb321c6..d6234c5 100644
--- a/libscan/util.h
+++ b/libscan/util.h
@@ -230,7 +230,7 @@ static int text_buffer_append_string(text_buffer_t *buf, const char *str, size_t
 
     if (len <= 4) {
         for (int i = 0; i < len; i++) {
-            if (((utf8_int32_t) 0xffffff80 & str[i]) == 0) {
+            if (((utf8_int32_t) 0xffffff80 & str[i]) == 0 && SHOULD_KEEP_CHAR(str[i])) {
                 dyn_buffer_write_char(&buf->dyn_buffer, str[i]);
             }
         }
diff --git a/third-party/utf8.h b/third-party/utf8.h
index b686b0c..fdcacc0 160000
--- a/third-party/utf8.h
+++ b/third-party/utf8.h
@@ -1 +1 @@
-Subproject commit b686b0c5181c2dd9f8297e6ac3692c9614b083be
+Subproject commit fdcacc00ff48f7d268108dfb0ec7ebc485f1eb16