diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index c674c5d606c546..e9d854a59efac5 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -61,9 +61,10 @@ jobs:
       - name: Build CPython
         run: |
           # Build Python with the libpython dynamic library
-          ./configure --with-pydebug --enable-shared
-          make -j4 regen-all
-          make regen-stdlib-module-names
+          ./configure --with-pydebug --enable-shared PYTHON_FOR_REGEN=./python
+          make -j4
+          LD_LIBRARY_PATH=. make -j4 regen-all
+          LD_LIBRARY_PATH=. make regen-stdlib-module-names
       - name: Check for changes
         run: |
           changes=$(git status --porcelain)
diff --git a/.travis.yml b/.travis.yml
index 6a22d20455b422..30cf7ce3851306 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -168,10 +168,9 @@ install:
 # Travis provides only 2 cores, so don't overdo the parallelism and waste memory.
 before_script:
   # -Og is much faster than -O0
-  - CFLAGS="${CFLAGS} -Og" ./configure --with-pydebug
-  - eval "$(pyenv init -)"
-  - pyenv global 3.8
-  - PYTHON_FOR_REGEN=python3.8 make -j4 regen-all
+  - CFLAGS="${CFLAGS} -Og" ./configure --with-pydebug PYTHON_FOR_REGEN=./python
+  - make -j4
+  - make -j4 regen-all
   - make regen-stdlib-module-names
   - changes=`git status --porcelain`
   - |
@@ -182,7 +181,6 @@ before_script:
         echo "$changes"
         exit 1
       fi
-  - make -j4
   - make pythoninfo
 
 script:
diff --git a/Lib/ctypes/test/test_values.py b/Lib/ctypes/test/test_values.py
index 44128298390d98..3c8f75fe1869fe 100644
--- a/Lib/ctypes/test/test_values.py
+++ b/Lib/ctypes/test/test_values.py
@@ -80,9 +80,9 @@ class struct_frozen(Structure):
                 continue
             items.append((entry.name.decode("ascii"), entry.size))
 
-        expected = [("__hello__", 125),
-                    ("__phello__", -125),
-                    ("__phello__.spam", 125),
+        expected = [("__hello__", 129),
+                    ("__phello__", -129),
+                    ("__phello__.spam", 129),
                     ]
         self.assertEqual(items, expected, "PyImport_FrozenModules example "
             "in Doc/library/ctypes.rst may be out of date")
diff --git a/Misc/NEWS.d/next/Build/2021-03-02-10-55-29.bpo-43372.2zXMGv.rst b/Misc/NEWS.d/next/Build/2021-03-02-10-55-29.bpo-43372.2zXMGv.rst
new file mode 100644
index 00000000000000..eeb685fc77a33d
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2021-03-02-10-55-29.bpo-43372.2zXMGv.rst
@@ -0,0 +1,3 @@
+Re-generate frozen code for ``__hello__`` using an up-to-date Python.  The
+marshal format for code objects has changed with bpo-42246, commit 877df851.
+Update expected code sizes in ctypes test_frozentable.
diff --git a/Python/frozen_hello.h b/Python/frozen_hello.h
index 9c566cc81ebf00..d58b726aa8b6cc 100644
--- a/Python/frozen_hello.h
+++ b/Python/frozen_hello.h
@@ -9,5 +9,5 @@ static unsigned char M___hello__[] = {
     100,218,5,112,114,105,110,116,169,0,114,2,0,
     0,0,114,2,0,0,0,218,4,110,111,110,101,
     218,8,60,109,111,100,117,108,101,62,1,0,0,
-    0,115,2,0,0,0,4,1,
+    0,115,6,0,0,0,4,0,12,1,255,128,
 };