diff --git a/setup/installers.py b/setup/installers.py
index 6a13e9491c..0ead78c82e 100644
--- a/setup/installers.py
+++ b/setup/installers.py
@@ -239,10 +239,10 @@ class ExtDev(Command):
         which, ext = opts.cli_args[:2]
         cmd = opts.cli_args[2:] or ['calibre-debug', '--test-build']
         if which == 'windows':
-            cp = subprocess.run([sys.executable, 'setup.py', 'build', '--cross-compile-extensions=windows', '--only=winspeech'])
+            cp = subprocess.run([sys.executable, 'setup.py', 'build', '--cross-compile-extensions=windows', f'--only={ext}'])
             if cp.returncode != 0:
                 raise SystemExit(cp.returncode)
-            src = 'src/calibre/plugins/winspeech.cross-windows-x64.pyd'
+            src = f'src/calibre/plugins/{ext}.cross-windows-x64.pyd'
             host = 'win'
             path = '/cygdrive/c/Program Files/Calibre2/app/bin/{}.pyd'
             bin_dir = '/cygdrive/c/Program Files/Calibre2'
diff --git a/src/calibre/utils/cpp_binding.h b/src/calibre/utils/cpp_binding.h
index 469b998eeb..8a3ee47c65 100644
--- a/src/calibre/utils/cpp_binding.h
+++ b/src/calibre/utils/cpp_binding.h
@@ -79,7 +79,7 @@ class wchar_raii : public generic_raii<wchar_t*, wchar_raii_free, static_cast<wc
 
 typedef generic_raii<PyObject*, Py_DecRef> pyobject_raii;
 
-template<typename T, void free_T(void*), size_t sz, T null=static_cast<T>(NULL)>
+template<typename T, void free_T(T), size_t sz, T null=static_cast<T>(NULL)>
 class generic_raii_array {
 	private:
 		generic_raii_array( const generic_raii_array & ) noexcept;