diff --git a/include/GLFW/glfw3.h b/include/GLFW/glfw3.h
index 1aae0a55..6ef01bf9 100644
--- a/include/GLFW/glfw3.h
+++ b/include/GLFW/glfw3.h
@@ -3903,6 +3903,8 @@ GLFWAPI void glfwRequestWindowAttention(GLFWwindow* window);
  *  The window should not be NULL.
  *
  *  @param[in] window The window to query.
+ *  @return The monitor, or `NULL` if the window is NULL or an
+ *  [error](@ref error_handling) occurred.
  *
  *  @errors Possible errors include @ref GLFW_NOT_INITIALIZED.
  *
diff --git a/src/win32_window.c b/src/win32_window.c
index 55d0ab9c..f81999a2 100644
--- a/src/win32_window.c
+++ b/src/win32_window.c
@@ -1772,7 +1772,7 @@ _GLFWmonitor* _glfwGetMonitorDisplayingWindowWin32(_GLFWwindow* window)
             return _glfw.monitors[i];
     }
 
-    return _glfw.monitors[0];
+    return NULL;
 }
 
 void _glfwFocusWindowWin32(_GLFWwindow* window)