diff --git a/CHANGELOG.md b/CHANGELOG.md
index be322b69..fa428099 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -62,6 +62,7 @@ In this document, Mod is Ctrl on Windows/Linux and Cmd on Mac.
 	- Improve thread safety of `dsp::RingBuffer`.
 	- Add several convenient filesystem routines to `system::`.
 	- Move all `string::` functions dealing with filesystem paths to `system::`.
+	- Change type of `Module::id` and `Cable::id` from `int` to `int64_t`.
 
 ### 1.1.6 (2019-11-04)
 - Add ability for plugins to use LuaJIT on Mac.
diff --git a/include/app/RackWidget.hpp b/include/app/RackWidget.hpp
index 25c9a59c..93b6cef3 100644
--- a/include/app/RackWidget.hpp
+++ b/include/app/RackWidget.hpp
@@ -57,7 +57,7 @@ struct RackWidget : widget::OpaqueWidget {
 	/** Moves a module to the closest non-colliding position */
 	void setModulePosNearest(ModuleWidget* mw, math::Vec pos);
 	void setModulePosForce(ModuleWidget* mw, math::Vec pos);
-	ModuleWidget* getModule(int moduleId);
+	ModuleWidget* getModule(int64_t moduleId);
 	bool isEmpty();
 	void updateModuleOldPositions();
 	history::ComplexAction* getModuleDragAction();
@@ -78,7 +78,7 @@ struct RackWidget : widget::OpaqueWidget {
 	CableWidget* releaseIncompleteCable();
 	/** Returns the most recently added complete cable connected to the given Port, i.e. the top of the stack. */
 	CableWidget* getTopCable(PortWidget* port);
-	CableWidget* getCable(int cableId);
+	CableWidget* getCable(int64_t cableId);
 	/** Returns all cables attached to port, complete or not. */
 	std::list<CableWidget*> getCablesOnPort(PortWidget* port);
 };
diff --git a/include/engine/Engine.hpp b/include/engine/Engine.hpp
index f07762a0..9fe601f6 100644
--- a/include/engine/Engine.hpp
+++ b/include/engine/Engine.hpp
@@ -67,8 +67,12 @@ struct Engine {
 
 	// Modules
 	size_t getNumModules();
-	void getModuleIds(int* moduleIds, int len);
-	std::vector<int> getModuleIds();
+	/** Fills `moduleIds` with up to `len` module IDs in the rack.
+	Returns the number of IDs written.
+	This C-like method does no allocations. The vector C++ version below does.
+	*/
+	size_t getModuleIds(int64_t* moduleIds, size_t len);
+	std::vector<int64_t> getModuleIds();
 	/** Adds a module to the rack engine.
 	The module ID must not be taken by another module.
 	If the module ID is -1, an ID is automatically assigned.
@@ -76,7 +80,7 @@ struct Engine {
 	*/
 	void addModule(Module* module);
 	void removeModule(Module* module);
-	Module* getModule(int moduleId);
+	Module* getModule(int64_t moduleId);
 	void resetModule(Module* module);
 	void randomizeModule(Module* module);
 	void bypassModule(Module* module, bool bypassed);
@@ -86,6 +90,9 @@ struct Engine {
 	void moduleFromJson(Module* module, json_t* rootJ);
 
 	// Cables
+	size_t getNumCables();
+	size_t getCableIds(int64_t* cableIds, size_t len);
+	std::vector<int64_t> getCableIds();
 	/** Adds a cable to the rack engine.
 	The cable ID must not be taken by another cable.
 	If the cable ID is -1, an ID is automatically assigned.
@@ -93,7 +100,7 @@ struct Engine {
 	*/
 	void addCable(Cable* cable);
 	void removeCable(Cable* cable);
-	Cable* getCable(int cableId);
+	Cable* getCable(int64_t cableId);
 
 	// Params
 	void setParam(Module* module, int paramId, float value);
@@ -110,14 +117,13 @@ struct Engine {
 	void removeParamHandle(ParamHandle* paramHandle);
 	/** Returns the unique ParamHandle for the given paramId
 	*/
-	ParamHandle* getParamHandle(int moduleId, int paramId);
-	/** Use getParamHandle(int, int) instead.
-	*/
+	ParamHandle* getParamHandle(int64_t moduleId, int paramId);
+	/** Use getParamHandle(moduleId, paramId) instead. */
 	DEPRECATED ParamHandle* getParamHandle(Module* module, int paramId);
 	/** Sets the ParamHandle IDs and module pointer.
 	If `overwrite` is true and another ParamHandle points to the same param, unsets that one and replaces it with the given handle.
 	*/
-	void updateParamHandle(ParamHandle* paramHandle, int moduleId, int paramId, bool overwrite = true);
+	void updateParamHandle(ParamHandle* paramHandle, int64_t moduleId, int paramId, bool overwrite = true);
 
 	json_t* toJson();
 	void fromJson(json_t* rootJ);
diff --git a/include/engine/Module.hpp b/include/engine/Module.hpp
index 26952c8a..e63c9a5e 100644
--- a/include/engine/Module.hpp
+++ b/include/engine/Module.hpp
@@ -50,7 +50,7 @@ struct Module {
 	/** Represents a message-passing channel for an adjacent module. */
 	struct Expander {
 		/** ID of the expander module, or -1 if nonexistent. */
-		int moduleId = -1;
+		int64_t moduleId = -1;
 		/** Pointer to the expander Module, or NULL if nonexistent. */
 		Module* module = NULL;
 		/** Double buffer for receiving messages from the expander module.
diff --git a/include/engine/ParamHandle.hpp b/include/engine/ParamHandle.hpp
index cae77e18..ac037309 100644
--- a/include/engine/ParamHandle.hpp
+++ b/include/engine/ParamHandle.hpp
@@ -14,7 +14,7 @@ struct ParamHandle {
 	/** Do not set these directly.
 	Use Engine ParamHandle methods.
 	*/
-	int moduleId = -1;
+	int64_t moduleId = -1;
 	int paramId = 0;
 	Module* module = NULL;
 
diff --git a/include/history.hpp b/include/history.hpp
index 30832795..33b64368 100644
--- a/include/history.hpp
+++ b/include/history.hpp
@@ -64,7 +64,7 @@ struct ComplexAction : Action {
 Subclass this to create your own custom actions for your module.
 */
 struct ModuleAction : Action {
-	int moduleId;
+	int64_t moduleId;
 };
 
 
@@ -135,10 +135,10 @@ struct ParamChange : ModuleAction {
 
 
 struct CableAdd : Action {
-	int cableId;
-	int inputModuleId;
+	int64_t cableId;
+	int64_t inputModuleId;
 	int inputId;
-	int outputModuleId;
+	int64_t outputModuleId;
 	int outputId;
 	NVGcolor color;
 	void setCable(app::CableWidget* cw);
diff --git a/src/app/RackWidget.cpp b/src/app/RackWidget.cpp
index aa6b886e..e9850eb6 100644
--- a/src/app/RackWidget.cpp
+++ b/src/app/RackWidget.cpp
@@ -182,11 +182,13 @@ void RackWidget::mergeJson(json_t* rootJ) {
 		json_t* idJ = json_object_get(moduleJ, "id");
 		if (!idJ)
 			continue;
-		int id = json_integer_value(idJ);
+		int64_t id = json_integer_value(idJ);
 		// TODO Legacy v0.6?
 		ModuleWidget* moduleWidget = getModule(id);
-		if (!moduleWidget)
+		if (!moduleWidget) {
+			WARN("Cannot find ModuleWidget with ID %ld", id);
 			continue;
+		}
 
 		// pos
 		math::Vec pos = moduleWidget->box.pos.minus(moduleOffset);
@@ -206,10 +208,12 @@ void RackWidget::mergeJson(json_t* rootJ) {
 		json_t* idJ = json_object_get(cableJ, "id");
 		if (!idJ)
 			continue;
-		int id = json_integer_value(idJ);
+		int64_t id = json_integer_value(idJ);
 		CableWidget* cw = getCable(id);
-		if (!cw)
+		if (!cw) {
+			WARN("Cannot find CableWidget with ID %ld", id);
 			continue;
+		}
 
 		json_t* cwJ = cw->toJson();
 		// Merge cable JSON object
@@ -230,10 +234,12 @@ void RackWidget::fromJson(json_t* rootJ) {
 		json_t* idJ = json_object_get(moduleJ, "id");
 		if (!idJ)
 			continue;
-		int id = json_integer_value(idJ);
+		int64_t id = json_integer_value(idJ);
 		engine::Module* module = APP->engine->getModule(id);
-		if (!module)
+		if (!module) {
+			WARN("Cannot find module with ID %ld", id);
 			continue;
+		}
 
 		ModuleWidget* moduleWidget = module->model->createModuleWidget(module);
 
@@ -273,10 +279,12 @@ void RackWidget::fromJson(json_t* rootJ) {
 		json_t* idJ = json_object_get(cableJ, "id");
 		if (!idJ)
 			continue;
-		int id = json_integer_value(idJ);
+		int64_t id = json_integer_value(idJ);
 		engine::Cable* cable = APP->engine->getCable(id);
-		if (!cable)
+		if (!cable) {
+			WARN("Cannot find cable with ID %ld", id);
 			continue;
+		}
 
 		CableWidget* cw = new CableWidget;
 		// Legacy: Before v1, cable colors were not serialized. So we need to initialize the color here.
@@ -515,7 +523,7 @@ void RackWidget::setModulePosForce(ModuleWidget* mw, math::Vec pos) {
 	RackWidget_updateAdjacent(this);
 }
 
-ModuleWidget* RackWidget::getModule(int moduleId) {
+ModuleWidget* RackWidget::getModule(int64_t moduleId) {
 	for (widget::Widget* w : moduleContainer->children) {
 		ModuleWidget* mw = dynamic_cast<ModuleWidget*>(w);
 		assert(mw);
@@ -648,7 +656,7 @@ CableWidget* RackWidget::getTopCable(PortWidget* port) {
 	return NULL;
 }
 
-CableWidget* RackWidget::getCable(int cableId) {
+CableWidget* RackWidget::getCable(int64_t cableId) {
 	for (widget::Widget* w : cableContainer->children) {
 		CableWidget* cw = dynamic_cast<CableWidget*>(w);
 		assert(cw);
diff --git a/src/core/MIDI_Map.cpp b/src/core/MIDI_Map.cpp
index 17ec545e..366c82bd 100644
--- a/src/core/MIDI_Map.cpp
+++ b/src/core/MIDI_Map.cpp
@@ -225,7 +225,7 @@ struct MIDI_Map : Module {
 		}
 	}
 
-	void learnParam(int id, int moduleId, int paramId) {
+	void learnParam(int id, int64_t moduleId, int paramId) {
 		APP->engine->updateParamHandle(&paramHandles[id], moduleId, paramId, true);
 		learnedParam = true;
 		commitLearn();
@@ -335,7 +335,7 @@ struct MIDI_MapChoice : LedDisplayChoice {
 		ParamWidget* touchedParam = APP->scene->rack->touchedParam;
 		if (touchedParam) {
 			APP->scene->rack->touchedParam = NULL;
-			int moduleId = touchedParam->module->id;
+			int64_t moduleId = touchedParam->module->id;
 			int paramId = touchedParam->paramId;
 			module->learnParam(id, moduleId, paramId);
 		}
diff --git a/src/engine/Cable.cpp b/src/engine/Cable.cpp
index 4f8b4f46..6dca57d2 100644
--- a/src/engine/Cable.cpp
+++ b/src/engine/Cable.cpp
@@ -23,7 +23,7 @@ void Cable::fromJson(json_t* rootJ) {
 	json_t* inputModuleIdJ = json_object_get(rootJ, "inputModuleId");
 	if (!inputModuleIdJ)
 		throw Exception("inputModuleId not found for cable");
-	int inputModuleId = json_integer_value(inputModuleIdJ);
+	int64_t inputModuleId = json_integer_value(inputModuleIdJ);
 	inputModule = APP->engine->getModule(inputModuleId);
 	if (!inputModule)
 		throw Exception("inputModule not found for cable");
@@ -38,7 +38,7 @@ void Cable::fromJson(json_t* rootJ) {
 	json_t* outputModuleIdJ = json_object_get(rootJ, "outputModuleId");
 	if (!outputModuleIdJ)
 		throw Exception("outputModuleId not found for cable");
-	int outputModuleId = json_integer_value(outputModuleIdJ);
+	int64_t outputModuleId = json_integer_value(outputModuleIdJ);
 	outputModule = APP->engine->getModule(outputModuleId);
 	if (!outputModule)
 		throw Exception("outputModule not found for cable");
diff --git a/src/engine/Engine.cpp b/src/engine/Engine.cpp
index 6d368448..12bb1fdc 100644
--- a/src/engine/Engine.cpp
+++ b/src/engine/Engine.cpp
@@ -188,11 +188,11 @@ struct Engine::Internal {
 	std::set<ParamHandle*> paramHandles;
 
 	// moduleId
-	std::map<int, Module*> modulesCache;
+	std::map<int64_t, Module*> modulesCache;
 	// cableId
-	std::map<int, Cable*> cablesCache;
+	std::map<int64_t, Cable*> cablesCache;
 	// (moduleId, paramId)
-	std::map<std::tuple<int, int>, ParamHandle*> paramHandlesCache;
+	std::map<std::tuple<int64_t, int>, ParamHandle*> paramHandlesCache;
 
 	float sampleRate = 0.f;
 	float sampleTime = 0.f;
@@ -657,21 +657,22 @@ size_t Engine::getNumModules() {
 }
 
 
-void Engine::getModuleIds(int* moduleIds, int len) {
+size_t Engine::getModuleIds(int64_t* moduleIds, size_t len) {
 	SharedLock lock(internal->mutex);
-	int i = 0;
+	size_t i = 0;
 	for (Module* m : internal->modules) {
 		if (i >= len)
 			break;
 		moduleIds[i] = m->id;
 		i++;
 	}
+	return i;
 }
 
 
-std::vector<int> Engine::getModuleIds() {
+std::vector<int64_t> Engine::getModuleIds() {
 	SharedLock lock(internal->mutex);
-	std::vector<int> moduleIds;
+	std::vector<int64_t> moduleIds;
 	moduleIds.reserve(internal->modules.size());
 	for (Module* m : internal->modules) {
 		moduleIds.push_back(m->id);
@@ -748,7 +749,7 @@ void Engine::removeModule(Module* module) {
 }
 
 
-Module* Engine::getModule(int moduleId) {
+Module* Engine::getModule(int64_t moduleId) {
 	SharedLock lock(internal->mutex);
 	auto it = internal->modulesCache.find(moduleId);
 	if (it == internal->modulesCache.end())
@@ -812,6 +813,35 @@ void Engine::moduleFromJson(Module* module, json_t* rootJ) {
 }
 
 
+size_t Engine::getNumCables() {
+	return internal->cables.size();
+}
+
+
+size_t Engine::getCableIds(int64_t* cableIds, size_t len) {
+	SharedLock lock(internal->mutex);
+	size_t i = 0;
+	for (Cable* c : internal->cables) {
+		if (i >= len)
+			break;
+		cableIds[i] = c->id;
+		i++;
+	}
+	return i;
+}
+
+
+std::vector<int64_t> Engine::getCableIds() {
+	SharedLock lock(internal->mutex);
+	std::vector<int64_t> cableIds;
+	cableIds.reserve(internal->cables.size());
+	for (Cable* c : internal->cables) {
+		cableIds.push_back(c->id);
+	}
+	return cableIds;
+}
+
+
 void Engine::addCable(Cable* cable) {
 	ExclusiveSharedLock lock(internal->mutex);
 	assert(cable);
@@ -893,7 +923,7 @@ void Engine::removeCable(Cable* cable) {
 }
 
 
-Cable* Engine::getCable(int cableId) {
+Cable* Engine::getCable(int64_t cableId) {
 	SharedLock lock(internal->mutex);
 	auto it = internal->cablesCache.find(cableId);
 	if (it == internal->cablesCache.end())
@@ -965,7 +995,7 @@ void Engine::removeParamHandle(ParamHandle* paramHandle) {
 }
 
 
-ParamHandle* Engine::getParamHandle(int moduleId, int paramId) {
+ParamHandle* Engine::getParamHandle(int64_t moduleId, int paramId) {
 	SharedLock lock(internal->mutex);
 	auto it = internal->paramHandlesCache.find(std::make_tuple(moduleId, paramId));
 	if (it == internal->paramHandlesCache.end())
@@ -979,7 +1009,7 @@ ParamHandle* Engine::getParamHandle(Module* module, int paramId) {
 }
 
 
-void Engine::updateParamHandle(ParamHandle* paramHandle, int moduleId, int paramId, bool overwrite) {
+void Engine::updateParamHandle(ParamHandle* paramHandle, int64_t moduleId, int paramId, bool overwrite) {
 	SharedLock lock(internal->mutex);
 	// Check that it exists
 	auto it = internal->paramHandles.find(paramHandle);