diff --git a/cpython-unix/build-cpython.sh b/cpython-unix/build-cpython.sh
index a95e3adfb..5c5c516d5 100755
--- a/cpython-unix/build-cpython.sh
+++ b/cpython-unix/build-cpython.sh
@@ -324,12 +324,11 @@ if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_14}" ]; then
     patch -p1 -i ${ROOT}/patch-python-relative-build-details.patch
 fi
 
-# Mark the COLORS global variable static to prevent it from
-# conflicting with the symbol in the ncurses library.
-# Fix has been merged upstream, drop in next 3.15 release
-# https://github.com/python/cpython/pull/143846
+# Mark _Py_jit_entry as extern in _testiternalcapi/interpreter.c to avoid a duplicate symbols.
+# The symbol is not actually used in the module, a better solution should be found, see:
+# https://github.com/python/cpython/issues/144712
 if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_15}" ]; then
-    patch -p1 -i ${ROOT}/patch-optimizer-static-colors.patch
+    patch -p1 -i ${ROOT}/patch-testinternalcapi-interpreter-extern.patch
 fi
 
 # Most bits look at CFLAGS. But setup.py only looks at CPPFLAGS.
diff --git a/cpython-unix/extension-modules.yml b/cpython-unix/extension-modules.yml
index 0bccd0f25..4dbde9107 100644
--- a/cpython-unix/extension-modules.yml
+++ b/cpython-unix/extension-modules.yml
@@ -652,6 +652,8 @@ _testinternalcapi:
       minimum-python-version: "3.13"
     - source: _testinternalcapi/complex.c
       minimum-python-version: "3.14"
+    - source: _testinternalcapi/interpreter.c
+      minimum-python-version: "3.15"
 
 _testmultiphase:
   minimum-python-version: '3.10'
diff --git a/cpython-unix/patch-optimizer-static-colors.patch b/cpython-unix/patch-optimizer-static-colors.patch
deleted file mode 100644
index 6b8ef77f1..000000000
--- a/cpython-unix/patch-optimizer-static-colors.patch
+++ /dev/null
@@ -1,13 +0,0 @@
-diff --git a/Python/optimizer.c b/Python/optimizer.c
-index a2a1feb8b9e..c5f47d7f22c 100644
---- a/Python/optimizer.c
-+++ b/Python/optimizer.c
-@@ -2009,7 +2009,7 @@ find_line_number(PyCodeObject *code, _PyExecutorObject *executor)
- #define BLACK "#000000"
- #define LOOP "#00c000"
- 
--const char *COLORS[10] = {
-+static const char *COLORS[10] = {
-     "9",
-     "8",
-     "7",
diff --git a/cpython-unix/patch-testinternalcapi-interpreter-extern.patch b/cpython-unix/patch-testinternalcapi-interpreter-extern.patch
new file mode 100644
index 000000000..4ddfc75c4
--- /dev/null
+++ b/cpython-unix/patch-testinternalcapi-interpreter-extern.patch
@@ -0,0 +1,13 @@
+diff --git a/Modules/_testinternalcapi/interpreter.c b/Modules/_testinternalcapi/interpreter.c
+index 2cd23fa3c58..653332f7073 100644
+--- a/Modules/_testinternalcapi/interpreter.c
++++ b/Modules/_testinternalcapi/interpreter.c
+@@ -21,7 +21,7 @@ stop_tracing_and_jit(PyThreadState *tstate, _PyInterpreterFrame *frame)
+ }
+ #endif
+ 
+-_PyJitEntryFuncPtr _Py_jit_entry;
++extern _PyJitEntryFuncPtr _Py_jit_entry;
+ 
+ #if _Py_TAIL_CALL_INTERP
+ #include "test_targets.h"
diff --git a/cpython-windows/build.py b/cpython-windows/build.py
index 3b27e6793..7b2cb301f 100644
--- a/cpython-windows/build.py
+++ b/cpython-windows/build.py
@@ -752,8 +752,7 @@ def run_msbuild(
         args.append("/property:DisableGil=true")
 
     # Build tail-calling Python for 3.15+
-    # TODO(jjh) Remove 'not freethreaded' when 3.15.0a6 released
-    if python_version.startswith("3.15") and platform == "x64" and not freethreaded:
+    if python_version.startswith("3.15") and platform == "x64":
         args.append("/property:PlatformToolset=v145")
         args.append("/property:UseTailCallInterp=true")
 
diff --git a/pythonbuild/downloads.py b/pythonbuild/downloads.py
index d17f02152..e7af6c069 100644
--- a/pythonbuild/downloads.py
+++ b/pythonbuild/downloads.py
@@ -93,10 +93,10 @@
         "python_tag": "cp314",
     },
     "cpython-3.15": {
-        "url": "https://www.python.org/ftp/python/3.15.0/Python-3.15.0a5.tar.xz",
-        "size": 34829268,
-        "sha256": "fee40da6450b67547c079dcb2852e8a03db6d57e06415466b2d3294449db22ef",
-        "version": "3.15.0a5",
+        "url": "https://www.python.org/ftp/python/3.15.0/Python-3.15.0a6.tar.xz",
+        "size": 34950024,
+        "sha256": "8e2a4e1b2afb93a84d659d431b1f384544b3da00a4b8ff5bf3580f07ad4ff989",
+        "version": "3.15.0a6",
         "licenses": ["Python-2.0", "CNRI-Python"],
         "license_file": "LICENSE.cpython.txt",
         "python_tag": "cp315",