diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5c914176b6..bddf979c21 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -130,13 +130,15 @@ ign_find_package(ignition-tools
 
 #--------------------------------------
 # Find protobuf
+# Module is needed to use the PROTOBUF_GENERATE_CPP
+set(protobuf_MODULE_COMPATIBLE TRUE)
 set(REQ_PROTOBUF_VER 3)
 ign_find_package(IgnProtobuf
                  VERSION ${REQ_PROTOBUF_VER}
                  REQUIRED
                  COMPONENTS all
                  PRETTY Protobuf)
-set(PROTOBUF_IMPORT_DIRS ${ignition-msgs7_INCLUDE_DIRS})
+set(Protobuf_IMPORT_DIRS ${ignition-msgs7_INCLUDE_DIRS})
 
 # Plugin install dirs
 set(IGNITION_GAZEBO_PLUGIN_INSTALL_DIR
diff --git a/include/ignition/gazebo/EntityComponentManager.hh b/include/ignition/gazebo/EntityComponentManager.hh
index 75e883f15a..90816df770 100644
--- a/include/ignition/gazebo/EntityComponentManager.hh
+++ b/include/ignition/gazebo/EntityComponentManager.hh
@@ -22,6 +22,7 @@
 
 #include <map>
 #include <memory>
+#include <optional>
 #include <set>
 #include <string>
 #include <typeinfo>
diff --git a/include/ignition/gazebo/EventManager.hh b/include/ignition/gazebo/EventManager.hh
index 7d466c5b09..0241bae447 100644
--- a/include/ignition/gazebo/EventManager.hh
+++ b/include/ignition/gazebo/EventManager.hh
@@ -47,13 +47,13 @@ namespace ignition
     /// occur.
     ///
     /// See \ref ignition::gazebo::events for a complete list of events.
-    class IGNITION_GAZEBO_VISIBLE EventManager
+    class EventManager
     {
       /// \brief Constructor
-      public: EventManager();
+      public: EventManager() = default;
 
       /// \brief Destructor
-      public: ~EventManager();
+      public: ~EventManager() = default;
 
       /// \brief Add a connection to an event.
       /// \param[in] _subscriber A std::function callback function. The function
diff --git a/include/ignition/gazebo/Server.hh b/include/ignition/gazebo/Server.hh
index 8387399ae3..ff8edae5b6 100644
--- a/include/ignition/gazebo/Server.hh
+++ b/include/ignition/gazebo/Server.hh
@@ -19,6 +19,7 @@
 
 #include <cstdint>
 #include <memory>
+#include <optional>
 #include <string>
 #include <ignition/gazebo/config.hh>
 #include <ignition/gazebo/EntityComponentManager.hh>
diff --git a/include/ignition/gazebo/World.hh b/include/ignition/gazebo/World.hh
index 1e902ef169..55d98ea54b 100644
--- a/include/ignition/gazebo/World.hh
+++ b/include/ignition/gazebo/World.hh
@@ -18,6 +18,7 @@
 #define IGNITION_GAZEBO_WORLD_HH_
 
 #include <memory>
+#include <optional>
 #include <string>
 #include <vector>
 
diff --git a/include/ignition/gazebo/detail/EntityComponentManager.hh b/include/ignition/gazebo/detail/EntityComponentManager.hh
index 880dba745c..cb6c2e368f 100644
--- a/include/ignition/gazebo/detail/EntityComponentManager.hh
+++ b/include/ignition/gazebo/detail/EntityComponentManager.hh
@@ -19,6 +19,7 @@
 
 #include <cstring>
 #include <map>
+#include <optional>
 #include <set>
 #include <type_traits>
 #include <utility>
diff --git a/include/ignition/gazebo/gui/GuiRunner.hh b/include/ignition/gazebo/gui/GuiRunner.hh
index 12fd1ae74c..8bb2ba7e7f 100644
--- a/include/ignition/gazebo/gui/GuiRunner.hh
+++ b/include/ignition/gazebo/gui/GuiRunner.hh
@@ -35,6 +35,7 @@ namespace gazebo
 inline namespace IGNITION_GAZEBO_VERSION_NAMESPACE {
 /// \brief Responsible for running GUI systems as new states are received from
 /// the backend.
+
 class IGNITION_GAZEBO_GUI_VISIBLE GuiRunner : public QObject
 {
   Q_OBJECT
diff --git a/include/ignition/gazebo/gui/GuiSystem.hh b/include/ignition/gazebo/gui/GuiSystem.hh
index c031101042..16ecdd1e09 100644
--- a/include/ignition/gazebo/gui/GuiSystem.hh
+++ b/include/ignition/gazebo/gui/GuiSystem.hh
@@ -41,7 +41,7 @@ namespace gazebo
   /// GUI systems are different from `ignition::gazebo::System`s because they
   /// don't run in the same process as the physics. Instead, they run in a
   /// separate process that is stepped by updates coming through the network
-  class IGNITION_GAZEBO_VISIBLE GuiSystem : public ignition::gui::Plugin
+  class GuiSystem : public ignition::gui::Plugin
   {
     Q_OBJECT
 
diff --git a/include/ignition/gazebo/gui/TmpIface.hh b/include/ignition/gazebo/gui/TmpIface.hh
index 8d339a887d..079b2946a5 100644
--- a/include/ignition/gazebo/gui/TmpIface.hh
+++ b/include/ignition/gazebo/gui/TmpIface.hh
@@ -36,7 +36,7 @@ namespace ignition
     /// Move API from here to their appropriate locations once that's known.
     ///
     /// This class should be removed before releasing!
-    class IGNITION_GAZEBO_VISIBLE TmpIface : public QObject
+    class TmpIface : public QObject
     {
       Q_OBJECT
 
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index d529e58d9e..4a87bfad90 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -42,7 +42,6 @@ set (sources
   Barrier.cc
   Conversions.cc
   EntityComponentManager.cc
-  EventManager.cc
   LevelManager.cc
   Link.cc
   Model.cc
@@ -86,6 +85,15 @@ set (gtest_sources
   network/NetworkManager_TEST.cc
 )
 
+if (MSVC)
+  # Warning #4251 is the "dll-interface" warning that tells you when types used
+  # by a class are not being exported. These generated source files have private
+  # members that don't get exported, so they trigger this warning. However, the
+  # warning is not important since those members do not need to be interfaced
+  # with.
+  set_source_files_properties(${sources} ${gtest_sources} COMPILE_FLAGS "/wd4251 /wd4146")
+endif()
+
 # Create the library target
 ign_create_core_library(SOURCES ${sources} CXX_STANDARD 17)
 target_link_libraries(${PROJECT_LIBRARY_TARGET_NAME}
@@ -102,7 +110,7 @@ target_link_libraries(${PROJECT_LIBRARY_TARGET_NAME}
   PRIVATE
   ignition-plugin${IGN_PLUGIN_VER}::loader
 )
-if (NOT APPLE)
+if (UNIX AND NOT APPLE)
   target_link_libraries(${PROJECT_LIBRARY_TARGET_NAME}
     PRIVATE stdc++fs)
 endif()
diff --git a/src/EventManager.cc b/src/EventManager.cc
deleted file mode 100644
index 656c816607..0000000000
--- a/src/EventManager.cc
+++ /dev/null
@@ -1,26 +0,0 @@
-/*
- * Copyright (C) 2018 Open Source Robotics Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
-*/
-#include "ignition/gazebo/EventManager.hh"
-
-using namespace ignition;
-using namespace gazebo;
-
-//////////////////////////////////////////////////
-EventManager::EventManager() = default;
-
-//////////////////////////////////////////////////
-EventManager::~EventManager() = default;
diff --git a/src/SdfGenerator.hh b/src/SdfGenerator.hh
index 5e267e9d9b..d0c2744c72 100644
--- a/src/SdfGenerator.hh
+++ b/src/SdfGenerator.hh
@@ -20,6 +20,7 @@
 #include <ignition/msgs/sdf_generator_config.pb.h>
 
 #include <sdf/Element.hh>
+#include <optional>
 #include <string>
 #include <unordered_map>
 
diff --git a/src/Server.cc b/src/Server.cc
index bb188ef993..aee4486823 100644
--- a/src/Server.cc
+++ b/src/Server.cc
@@ -15,6 +15,8 @@
  *
 */
 
+#include <numeric>
+
 #include <ignition/common/SystemPaths.hh>
 #include <ignition/fuel_tools/Interface.hh>
 #include <ignition/fuel_tools/ClientConfig.hh>
diff --git a/src/ServerPrivate.hh b/src/ServerPrivate.hh
index c8980291c4..7aeae8a033 100644
--- a/src/ServerPrivate.hh
+++ b/src/ServerPrivate.hh
@@ -23,6 +23,7 @@
 #include <condition_variable>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <thread>
 #include <unordered_map>
diff --git a/src/SimulationRunner.hh b/src/SimulationRunner.hh
index faf8e3518b..8e40106bbd 100644
--- a/src/SimulationRunner.hh
+++ b/src/SimulationRunner.hh
@@ -26,6 +26,7 @@
 #include <functional>
 #include <list>
 #include <memory>
+#include <optional>
 #include <string>
 #include <unordered_map>
 #include <unordered_set>
diff --git a/src/gui/GuiFileHandler.hh b/src/gui/GuiFileHandler.hh
index 017a575346..981b9fb769 100644
--- a/src/gui/GuiFileHandler.hh
+++ b/src/gui/GuiFileHandler.hh
@@ -36,7 +36,7 @@ inline namespace IGNITION_GAZEBO_VERSION_NAMESPACE {
 namespace gui
 {
 /// \brief Class for handling saving and loading of SDFormat files
-class IGNITION_GAZEBO_VISIBLE GuiFileHandler : public QObject
+class GuiFileHandler : public QObject
 {
   Q_OBJECT
 
diff --git a/src/gui/PathManager.hh b/src/gui/PathManager.hh
index 2247916a60..341e382cf2 100644
--- a/src/gui/PathManager.hh
+++ b/src/gui/PathManager.hh
@@ -35,7 +35,7 @@ namespace gui
 /// \brief Class for handling paths and their environment variables.
 /// It queries the server for paths at startup, and keeps paths updated
 /// whenever they change in the server.
-class IGNITION_GAZEBO_VISIBLE PathManager : public QObject
+class PathManager : public QObject
 {
   Q_OBJECT
 
diff --git a/src/gui/plugins/align_tool/AlignTool.cc b/src/gui/plugins/align_tool/AlignTool.cc
index e2b7084e8a..e2c41740fb 100644
--- a/src/gui/plugins/align_tool/AlignTool.cc
+++ b/src/gui/plugins/align_tool/AlignTool.cc
@@ -24,6 +24,7 @@
 #include <queue>
 #include <string>
 #include <vector>
+
 #include <ignition/gui/Application.hh>
 #include <ignition/gui/MainWindow.hh>
 #include <ignition/common/Console.hh>
diff --git a/src/gui/plugins/resource_spawner/ResourceSpawner.hh b/src/gui/plugins/resource_spawner/ResourceSpawner.hh
index d95e5727cb..2dd222534e 100644
--- a/src/gui/plugins/resource_spawner/ResourceSpawner.hh
+++ b/src/gui/plugins/resource_spawner/ResourceSpawner.hh
@@ -18,6 +18,7 @@
 #ifndef IGNITION_GAZEBO_GUI_RESOURCE_SPAWNER_HH_
 #define IGNITION_GAZEBO_GUI_RESOURCE_SPAWNER_HH_
 
+#include <algorithm>
 #include <memory>
 #include <string>
 #include <vector>
diff --git a/src/systems/CMakeLists.txt b/src/systems/CMakeLists.txt
index c5eeabe6e7..1427a96125 100644
--- a/src/systems/CMakeLists.txt
+++ b/src/systems/CMakeLists.txt
@@ -62,12 +62,16 @@ function(gz_add_system system_name)
   # files, we also install an unversioned symlink into the same versioned folder.
   set(versioned ${CMAKE_SHARED_LIBRARY_PREFIX}${system_target}${CMAKE_SHARED_LIBRARY_SUFFIX})
   set(unversioned ${CMAKE_SHARED_LIBRARY_PREFIX}${PROJECT_NAME_NO_VERSION_LOWER}-${system_name}${CMAKE_SHARED_LIBRARY_SUFFIX})
-  if (WIN32)
-    # create_symlink requires cmake 3.13 on windows
-    cmake_minimum_required(VERSION 3.13 FATAL_ERROR)
+  if(WIN32)
+    # symlinks on Windows require admin priviledges, fallback to copy
+    ADD_CUSTOM_COMMAND(TARGET ${system_target} POST_BUILD
+      COMMAND "${CMAKE_COMMAND}" -E copy
+        "$<TARGET_FILE:${system_target}>"
+        "$<TARGET_FILE_DIR:${system_target}>/${unversioned}")
+  else()
+    EXECUTE_PROCESS(COMMAND ${CMAKE_COMMAND} -E create_symlink ${versioned} ${unversioned})
+    INSTALL(FILES ${PROJECT_BINARY_DIR}/${unversioned} DESTINATION ${IGNITION_GAZEBO_PLUGIN_INSTALL_DIR})
   endif()
-  EXECUTE_PROCESS(COMMAND ${CMAKE_COMMAND} -E create_symlink ${versioned} ${unversioned})
-  INSTALL(FILES ${PROJECT_BINARY_DIR}/${unversioned} DESTINATION ${IGNITION_GAZEBO_PLUGIN_INSTALL_DIR})
 endfunction()
 
 add_subdirectory(air_pressure)
diff --git a/test/integration/entity_erase.cc b/test/integration/entity_erase.cc
index bb017612a4..24384c1eb1 100644
--- a/test/integration/entity_erase.cc
+++ b/test/integration/entity_erase.cc
@@ -17,6 +17,8 @@
 
 #include <gtest/gtest.h>
 
+#include <optional>
+
 #include "ignition/gazebo/Server.hh"
 #include "ignition/gazebo/test_config.hh"  // NOLINT(build/include)