diff --git a/termstr/termstr.py b/termstr/termstr.py
index 887fbc0..4e868bd 100644
--- a/termstr/termstr.py
+++ b/termstr/termstr.py
@@ -173,13 +173,13 @@ _ZERO_WIDTH_SPACE = "\u200b"
 
 
 def _pad_wide_chars(str_):
-    parts = []
-    last_width = None
-    for char in str_:
-        width = cwcwidth.wcwidth(char)
-        parts.append(f"{_ZERO_WIDTH_SPACE}{char}" if width != 0 and last_width == 2 else char)
-        last_width = width
-    padded_str = "".join(parts)
+    def parts():
+        last_width = None
+        for char in str_:
+            width = cwcwidth.wcwidth(char)
+            yield f"{_ZERO_WIDTH_SPACE}{char}" if width != 0 and last_width == 2 else char
+            last_width = width
+    padded_str = "".join(parts())
     if len(padded_str) > 0 and cwcwidth.wcwidth(padded_str[-1]) == 2:
         padded_str += _ZERO_WIDTH_SPACE
     return str_ if len(padded_str) == len(str_) else padded_str