diff --git a/Lib/turtle.py b/Lib/turtle.py
index 599f645fd0c..3d1d3b060d3 100644
--- a/Lib/turtle.py
+++ b/Lib/turtle.py
@@ -2945,7 +2945,7 @@ def shapetransform(self, t11=None, t12=None, t21=None, t22=None):
         self._stretchfactor = a11, a22
         self._shearfactor = a12/a22
         self._tilt = alfa
-        self._update()
+        self.pen(resizemode="user")
 
 
     def _polytrafo(self, poly):
diff --git a/Misc/ACKS b/Misc/ACKS
index c42b02b9ef6..9787d8e74b8 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -235,6 +235,7 @@ Ingrid Cheung
 Albert Chin-A-Young
 Adal Chiriliuc
 Matt Chisholm
+Lita Cho
 Anders Chrigström
 Tom Christiansen
 Vadim Chugunov
diff --git a/Misc/NEWS b/Misc/NEWS
index a94d0735155..848eb863393 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -29,6 +29,9 @@ Library
 
 - Issue #21491: socketserver: Fix a race condition in child processes reaping.
 
+- Issue #21812: turtle.shapetransform did not tranform the turtle on the
+  first call.  (Issue identified and fixed by Lita Cho.)
+
 - Issue #21635:  The difflib SequenceMatcher.get_matching_blocks() method
   cache didn't match the actual result.  The former was a list of tuples
   and the latter was a list of named tuples.