diff --git a/addon/globalPlugins/MathCAT/MathCAT.py b/addon/globalPlugins/MathCAT/MathCAT.py
index 62760fcc..388f103f 100644
--- a/addon/globalPlugins/MathCAT/MathCAT.py
+++ b/addon/globalPlugins/MathCAT/MathCAT.py
@@ -22,7 +22,7 @@
 import winKernel
 import gui
 
-from . import libmathcat_py as libmathcat
+from ._libmathcat_loader import libmathcat
 from typing import Type
 from collections.abc import Generator, Callable
 from keyboardHandler import KeyboardInputGesture  # navigation key strokes
diff --git a/addon/globalPlugins/MathCAT/MathCATPreferences.py b/addon/globalPlugins/MathCAT/MathCATPreferences.py
index 0012ccb0..4ba594a5 100644
--- a/addon/globalPlugins/MathCAT/MathCATPreferences.py
+++ b/addon/globalPlugins/MathCAT/MathCATPreferences.py
@@ -808,7 +808,7 @@ def writeUserPreferences() -> None:
 		folder exists, and saves the preferences to disk.
 		"""
 		# Language is special because it is set elsewhere by SetPreference which overrides the user_prefs -- so set it here
-		from . import libmathcat_py as libmathcat
+		from ._libmathcat_loader import libmathcat
 
 		try:
 			libmathcat.SetPreference("Language", userPreferences["Speech"]["Language"])
diff --git a/addon/globalPlugins/MathCAT/_libmathcat_loader.py b/addon/globalPlugins/MathCAT/_libmathcat_loader.py
new file mode 100644
index 00000000..88c25fea
--- /dev/null
+++ b/addon/globalPlugins/MathCAT/_libmathcat_loader.py
@@ -0,0 +1,19 @@
+# -*- coding: UTF-8 -*-
+
+"""Loads the libmathcat_py extension module matching the running process's bitness.
+
+Both a 32-bit and a 64-bit build of libmathcat_py ship in this addon so a single
+package works under both 32-bit and 64-bit NVDA.
+"""
+
+import importlib.util
+import os
+import sys
+
+# checking for 64 vs 32-bit: https://docs.python.org/3/library/platform.html#cross-platform
+_bitness = "x64" if sys.maxsize > 2**32 else "x86"
+_pyd_path = os.path.join(os.path.dirname(__file__), f"libmathcat_py_{_bitness}.pyd")
+
+_spec = importlib.util.spec_from_file_location("libmathcat_py", _pyd_path)
+libmathcat = importlib.util.module_from_spec(_spec)
+_spec.loader.exec_module(libmathcat)
diff --git a/addon/globalPlugins/MathCAT/libmathcat_py.pyd b/addon/globalPlugins/MathCAT/libmathcat_py.pyd
deleted file mode 100644
index 9c1f2b1d..00000000
Binary files a/addon/globalPlugins/MathCAT/libmathcat_py.pyd and /dev/null differ
diff --git a/addon/globalPlugins/MathCAT/libmathcat_py_x64.pyd b/addon/globalPlugins/MathCAT/libmathcat_py_x64.pyd
new file mode 100644
index 00000000..852feca2
Binary files /dev/null and b/addon/globalPlugins/MathCAT/libmathcat_py_x64.pyd differ
diff --git a/build-nvda-addon.sh b/build-nvda-addon.sh
index c5c7c4fc..3c5cc86e 100644
--- a/build-nvda-addon.sh
+++ b/build-nvda-addon.sh
@@ -6,7 +6,7 @@ STFLAGS='-C linker=lld'
 PYO3_PYTHON=$YO3_PYTHON_32/python.exe STFLAGS="$STFLAGS" cargo build --target i686-pc-windows-msvc --release
 
 
-cp target/i686-pc-windows-msvc/release/libmathcat_py.dll addon/globalPlugins/MathCAT/libmathcat_py.pyd
+cp target/i686-pc-windows-msvc/release/libmathcat_py.dll addon/globalPlugins/MathCAT/libmathcat_py_x86.pyd
 
 # for testing
 cp target/i686-pc-windows-msvc/release/libmathcat_py.dll Example/libmathcat_py.pyd
diff --git a/build64-nvda-addon.sh b/build64-nvda-addon.sh
index 56bc30e7..6f8c4904 100644
--- a/build64-nvda-addon.sh
+++ b/build64-nvda-addon.sh
@@ -8,9 +8,9 @@ echo "before cargo build"
 PYO3_PYTHON=${PYO3_PYTHON_64}/python.exe STFLAGS="$STFLAGS" cargo build --target x86_64-pc-windows-msvc --release
 echo "after cargo build"
 
-echo "before cp target/x86_64-pc-windows-msvc/release/libmathcat_py.dll addon/globalPlugins/MathCAT/libmathcat_py.pyd"
+echo "before cp target/x86_64-pc-windows-msvc/release/libmathcat_py.dll addon/globalPlugins/MathCAT/libmathcat_py_x64.pyd"
 
-cp target/x86_64-pc-windows-msvc/release/libmathcat_py.dll addon/globalPlugins/MathCAT/libmathcat_py.pyd
+cp target/x86_64-pc-windows-msvc/release/libmathcat_py.dll addon/globalPlugins/MathCAT/libmathcat_py_x64.pyd
 
 # for testing
 cp target/x86_64-pc-windows-msvc/release/libmathcat_py.dll Example/libmathcat_py.pyd
diff --git a/buildVars.py b/buildVars.py
index c35304d6..c3117ffa 100644
--- a/buildVars.py
+++ b/buildVars.py
@@ -44,7 +44,7 @@ def _(arg):
     # Documentation file name
     "addon_docFileName": "readme.html",
     # Minimum NVDA version supported (e.g. "2018.3.0", minor version is optional)
-    "addon_minimumNVDAVersion": "2026.1",
+    "addon_minimumNVDAVersion": "2025.1",
     # Last NVDA version supported/tested (e.g. "2018.4.0", ideally more recent than minimum version)
     "addon_lastTestedNVDAVersion": "2026.1",
     # Add-on update channel (default is None, denoting stable releases,