diff --git a/src/codegen/Index.go b/src/codegen/Index.go
new file mode 100644
index 0000000..fec046f
--- /dev/null
+++ b/src/codegen/Index.go
@@ -0,0 +1,4 @@
+package codegen
+
+// Index is the data type for storing step indices.
+type Index uint16
\ No newline at end of file
diff --git a/src/codegen/Step.go b/src/codegen/Step.go
index 93e5eda..f48cc00 100644
--- a/src/codegen/Step.go
+++ b/src/codegen/Step.go
@@ -13,7 +13,7 @@ type Step struct {
 	Phis     set.Ordered[*Step]
 	Live     []*Step
 	Hints    []cpu.Register
-	Index    int
+	Index    Index
 	Register cpu.Register
 }
 
diff --git a/src/codegen/createSteps.go b/src/codegen/createSteps.go
index 87bdc6b..04a97da 100644
--- a/src/codegen/createSteps.go
+++ b/src/codegen/createSteps.go
@@ -9,7 +9,7 @@ func createSteps(ir ssa.IR) IR {
 	steps := make([]*Step, count)
 	valueToStep := make(map[ssa.Value]*Step, count)
 	blockToRegion := make(map[*ssa.Block]region, len(ir.Blocks))
-	i := 0
+	i := Index(0)
 
 	for _, block := range ir.Blocks {
 		if block != ir.Blocks[0] {
@@ -24,7 +24,7 @@ func createSteps(ir ssa.IR) IR {
 
 		blockToRegion[block] = region{
 			Start: uint32(i),
-			End:   uint32(i + len(block.Instructions)),
+			End:   uint32(i + Index(len(block.Instructions))),
 		}
 
 		for _, instr := range block.Instructions {
diff --git a/src/codegen/reorderParameters.go b/src/codegen/reorderParameters.go
index b0e194f..87fc231 100644
--- a/src/codegen/reorderParameters.go
+++ b/src/codegen/reorderParameters.go
@@ -22,7 +22,7 @@ func (f *Function) reorderParameters() {
 			bringToFront(f.Steps[:i+1], i)
 
 			for h := range i + 1 {
-				f.Steps[h].Index = h
+				f.Steps[h].Index = Index(h)
 			}
 
 			if usedRegisters&(1<<step.Register) != 0 {
diff --git a/src/codegen/reorderPhis.go b/src/codegen/reorderPhis.go
index 5fbc185..4d9091d 100644
--- a/src/codegen/reorderPhis.go
+++ b/src/codegen/reorderPhis.go
@@ -15,7 +15,7 @@ func (f *Function) reorderPhis() {
 
 		switch {
 		case isPhi && start == -1:
-			start = step.Index
+			start = int(step.Index)
 		case !isPhi && start != -1:
 			end := step.Index
 			phis := f.Steps[start:end]
@@ -32,7 +32,7 @@ func (f *Function) reorderPhis() {
 					cmp := aIndex - bIndex
 
 					if cmp != 0 {
-						return cmp
+						return int(cmp)
 					}
 				}
 
@@ -40,7 +40,7 @@ func (f *Function) reorderPhis() {
 			})
 
 			for i, phi := range phis {
-				phi.Index = start + i
+				phi.Index = Index(start + i)
 			}
 
 			start = -1
diff --git a/src/verbose/SSA.go b/src/verbose/SSA.go
index 1232000..5e3ce4b 100644
--- a/src/verbose/SSA.go
+++ b/src/verbose/SSA.go
@@ -96,7 +96,7 @@ func SSA(root *core.Function) {
 				ansi.Dim.Printf("live: ")
 
 				slices.SortStableFunc(step.Live, func(a *codegen.Step, b *codegen.Step) int {
-					return a.Index - b.Index
+					return int(a.Index - b.Index)
 				})
 
 				for _, live := range step.Live {