diff --git a/Changelog b/Changelog
index 221ab862..0f8adc98 100644
--- a/Changelog
+++ b/Changelog
@@ -2,6 +2,7 @@
  - Introduce DockWidget::setFloatingWindowFlags(flags). Allows for different
    FloatingWindows to have different window flags. For example, some having
    Qt::Tool while others having Qt::Window (#314).
+ - Fixed fixed-sized windows being able to be resized on Windows (#345)
 
 * v1.6.0 (14 September 2022)
  - Minimum Qt6 version is now 6.2.0
diff --git a/src/private/WidgetResizeHandler.cpp b/src/private/WidgetResizeHandler.cpp
index 59e4cd72..a8909db8 100644
--- a/src/private/WidgetResizeHandler.cpp
+++ b/src/private/WidgetResizeHandler.cpp
@@ -369,6 +369,7 @@ bool WidgetResizeHandler::handleWindowsNativeEvent(QWindow *w, MSG *msg,
         const int borderWidth = 8;
         const bool hasFixedWidth = w->minimumWidth() == w->maximumWidth();
         const bool hasFixedHeight = w->minimumHeight() == w->maximumHeight();
+        const bool hasFixedWidthOrHeight = hasFixedWidth || hasFixedHeight;
 
         *result = 0;
         const int xPos = GET_X_LPARAM(msg->lParam);
@@ -376,13 +377,13 @@ bool WidgetResizeHandler::handleWindowsNativeEvent(QWindow *w, MSG *msg,
         RECT rect;
         GetWindowRect(reinterpret_cast<HWND>(w->winId()), &rect);
 
-        if (xPos >= rect.left && xPos <= rect.left + borderWidth && yPos <= rect.bottom && yPos >= rect.bottom - borderWidth && features.hasResize()) {
+        if (!hasFixedWidthOrHeight && xPos >= rect.left && xPos <= rect.left + borderWidth && yPos <= rect.bottom && yPos >= rect.bottom - borderWidth && features.hasResize()) {
             *result = HTBOTTOMLEFT;
-        } else if (xPos < rect.right && xPos >= rect.right - borderWidth && yPos <= rect.bottom && yPos >= rect.bottom - borderWidth && features.hasResize()) {
+        } else if (!hasFixedWidthOrHeight && xPos < rect.right && xPos >= rect.right - borderWidth && yPos <= rect.bottom && yPos >= rect.bottom - borderWidth && features.hasResize()) {
             *result = HTBOTTOMRIGHT;
-        } else if (xPos >= rect.left && xPos <= rect.left + borderWidth && yPos >= rect.top && yPos <= rect.top + borderWidth && features.hasResize()) {
+        } else if (!hasFixedWidthOrHeight && xPos >= rect.left && xPos <= rect.left + borderWidth && yPos >= rect.top && yPos <= rect.top + borderWidth && features.hasResize()) {
             *result = HTTOPLEFT;
-        } else if (xPos <= rect.right && xPos >= rect.right - borderWidth && yPos >= rect.top && yPos < rect.top + borderWidth && features.hasResize()) {
+        } else if (!hasFixedWidthOrHeight && xPos <= rect.right && xPos >= rect.right - borderWidth && yPos >= rect.top && yPos < rect.top + borderWidth && features.hasResize()) {
             *result = HTTOPRIGHT;
         } else if (!hasFixedWidth && xPos >= rect.left && xPos <= rect.left + borderWidth && features.hasResize()) {
             *result = HTLEFT;