diff --git a/include/avian/codegen/architecture.h b/include/avian/codegen/architecture.h
index 756a67012c..eabe7542dd 100644
--- a/include/avian/codegen/architecture.h
+++ b/include/avian/codegen/architecture.h
@@ -85,7 +85,7 @@ class Architecture {
   virtual bool argumentAlignment() = 0;
   virtual bool argumentRegisterAlignment() = 0;
   virtual unsigned argumentRegisterCount() = 0;
-  virtual int argumentRegister(unsigned index) = 0;
+  virtual Register argumentRegister(unsigned index) = 0;
 
   virtual bool hasLinkRegister() = 0;
 
diff --git a/include/avian/codegen/assembler.h b/include/avian/codegen/assembler.h
index a233fa82bf..06179aa777 100644
--- a/include/avian/codegen/assembler.h
+++ b/include/avian/codegen/assembler.h
@@ -53,10 +53,10 @@ class Assembler {
  public:
   class Client {
    public:
-    virtual int acquireTemporary(RegisterMask mask = ~static_cast<RegisterMask>(0)) = 0;
-    virtual void releaseTemporary(int r) = 0;
+    virtual Register acquireTemporary(RegisterMask mask = ~static_cast<RegisterMask>(0)) = 0;
+    virtual void releaseTemporary(Register r) = 0;
 
-    virtual void save(int r) = 0;
+    virtual void save(Register r) = 0;
   };
 
   class Block {
diff --git a/include/avian/codegen/registers.h b/include/avian/codegen/registers.h
index 0ddbf6e7dd..19261f0f23 100644
--- a/include/avian/codegen/registers.h
+++ b/include/avian/codegen/registers.h
@@ -17,6 +17,7 @@ namespace avian {
 namespace codegen {
 
 typedef uint64_t RegisterMask;
+typedef int Register;
 
 class BoundedRegisterMask {
  public:
@@ -62,7 +63,7 @@ class RegisterIterator {
     return index < mask.limit;
   }
 
-  inline int next()
+  inline Register next()
   {
     int r = index;
     do {
diff --git a/src/codegen/compiler.cpp b/src/codegen/compiler.cpp
index d4f05b4f8e..32047d52fc 100644
--- a/src/codegen/compiler.cpp
+++ b/src/codegen/compiler.cpp
@@ -2210,22 +2210,22 @@ class Client : public Assembler::Client {
   {
   }
 
-  virtual int acquireTemporary(RegisterMask mask)
+  virtual Register acquireTemporary(RegisterMask mask)
   {
     unsigned cost;
-    int r = pickRegisterTarget(c, 0, mask, &cost);
+    Register r = pickRegisterTarget(c, 0, mask, &cost);
     expect(c, cost < Target::Impossible);
     save(r);
     c->registerResources[r].increment(c);
     return r;
   }
 
-  virtual void releaseTemporary(int r)
+  virtual void releaseTemporary(Register r)
   {
     c->registerResources[r].decrement(c);
   }
 
-  virtual void save(int r)
+  virtual void save(Register r)
   {
     RegisterResource* reg = c->registerResources + r;
 
diff --git a/src/codegen/compiler/event.cpp b/src/codegen/compiler/event.cpp
index e2312db18f..789d470f44 100644
--- a/src/codegen/compiler/event.cpp
+++ b/src/codegen/compiler/event.cpp
@@ -396,7 +396,7 @@ class CallEvent : public Event {
         SiteMask targetMask;
         if (index + (c->arch->argumentRegisterAlignment() ? footprint : 1)
             <= c->arch->argumentRegisterCount()) {
-          int number = c->arch->argumentRegister(index);
+          Register number = c->arch->argumentRegister(index);
 
           if (DebugReads) {
             fprintf(stderr, "reg %d arg read %p\n", number, v);
diff --git a/src/codegen/compiler/regalloc.cpp b/src/codegen/compiler/regalloc.cpp
index 52ff8f8da5..5f597537b8 100644
--- a/src/codegen/compiler/regalloc.cpp
+++ b/src/codegen/compiler/regalloc.cpp
@@ -57,10 +57,10 @@ unsigned resourceCost(Context* c,
 }
 
 bool pickRegisterTarget(Context* c,
-                        int i,
+                        Register i,
                         Value* v,
                         RegisterMask mask,
-                        int* target,
+                        Register* target,
                         unsigned* cost,
                         CostCalculator* costCalculator)
 {
@@ -85,17 +85,17 @@ bool pickRegisterTarget(Context* c,
   return false;
 }
 
-int pickRegisterTarget(Context* c,
+Register pickRegisterTarget(Context* c,
                        Value* v,
                        RegisterMask mask,
                        unsigned* cost,
                        CostCalculator* costCalculator)
 {
-  int target = lir::NoRegister;
+  Register target = lir::NoRegister;
   *cost = Target::Impossible;
 
   if (mask & c->regFile->generalRegisters.mask) {
-    for (int i = c->regFile->generalRegisters.limit - 1;
+    for (Register i = c->regFile->generalRegisters.limit - 1;
          i >= c->regFile->generalRegisters.start;
          --i) {
       if (pickRegisterTarget(c, i, v, mask, &target, cost, costCalculator)) {
@@ -105,8 +105,8 @@ int pickRegisterTarget(Context* c,
   }
 
   if (mask & c->regFile->floatRegisters.mask) {
-    for (int i = c->regFile->floatRegisters.start;
-         i < static_cast<int>(c->regFile->floatRegisters.limit);
+    for (Register i = c->regFile->floatRegisters.start;
+         i < static_cast<Register>(c->regFile->floatRegisters.limit);
          ++i) {
       if (pickRegisterTarget(c, i, v, mask, &target, cost, costCalculator)) {
         return i;
@@ -123,7 +123,7 @@ Target pickRegisterTarget(Context* c,
                           CostCalculator* costCalculator)
 {
   unsigned cost;
-  int number = pickRegisterTarget(c, v, mask, &cost, costCalculator);
+  Register number = pickRegisterTarget(c, v, mask, &cost, costCalculator);
   return Target(number, lir::RegisterOperand, cost);
 }
 
diff --git a/src/codegen/compiler/regalloc.h b/src/codegen/compiler/regalloc.h
index 6aa782ab04..e512e63183 100644
--- a/src/codegen/compiler/regalloc.h
+++ b/src/codegen/compiler/regalloc.h
@@ -55,7 +55,7 @@ class Target {
   {
   }
 
-  Target(int index, lir::OperandType type, unsigned cost)
+  Target(Register index, lir::OperandType type, unsigned cost)
       : index(index), type(type), cost(cost)
   {
   }