diff --git a/extern/Nuked-OPL3 b/extern/Nuked-OPL3
new file mode 160000
index 000000000..bb5c8d08a
--- /dev/null
+++ b/extern/Nuked-OPL3
@@ -0,0 +1 @@
+Subproject commit bb5c8d08a85779c42b75c79d7b84f365a1b93b66
diff --git a/extern/imgui b/extern/imgui
new file mode 160000
index 000000000..1ee252772
--- /dev/null
+++ b/extern/imgui
@@ -0,0 +1 @@
+Subproject commit 1ee252772ae9c0a971d06257bb5c89f628fa696a
diff --git a/src/engine/platform/sound/es550x/util.hpp b/src/engine/platform/sound/es550x/util.hpp
index 63d082ac0..ad85fdf99 100644
--- a/src/engine/platform/sound/es550x/util.hpp
+++ b/src/engine/platform/sound/es550x/util.hpp
@@ -12,6 +12,7 @@
 
 #pragma once
 
+#include <iterator>
 #include <algorithm>
 #include <memory>