diff --git a/src/asm/Assembler.go b/src/asm/Assembler.go
index 6cc94fc..2a4323b 100644
--- a/src/asm/Assembler.go
+++ b/src/asm/Assembler.go
@@ -78,7 +78,12 @@ func (a *Assembler) Merge(b *Assembler) {
 	}
 
 	a.Instructions = append(a.Instructions, b.Instructions[skip:]...)
-	maps.Copy(a.Data, b.Data)
+
+	if a.Data == nil {
+		a.Data = b.Data
+	} else {
+		maps.Copy(a.Data, b.Data)
+	}
 
 	for library := range b.Libraries.All() {
 		for _, fn := range library.Functions {
diff --git a/src/asm/Assembler_test.go b/src/asm/Assembler_test.go
index ced676e..fa09104 100644
--- a/src/asm/Assembler_test.go
+++ b/src/asm/Assembler_test.go
@@ -6,6 +6,7 @@ import (
 	"git.urbach.dev/cli/q/src/asm"
 	"git.urbach.dev/cli/q/src/config"
 	"git.urbach.dev/cli/q/src/cpu"
+	"git.urbach.dev/cli/q/src/token"
 	"git.urbach.dev/go/assert"
 )
 
@@ -18,11 +19,13 @@ func TestAssembler(t *testing.T) {
 	a.Append(&asm.Jump{Label: "d"})
 	a.Append(&asm.Jump{Label: "e"})
 	a.Append(&asm.Jump{Label: "f"})
+	a.Append(&asm.Jump{Label: "g"})
 	a.Append(&asm.Call{Label: "b"})
 	a.Append(&asm.Call{Label: "c"})
 	a.Append(&asm.Call{Label: "d"})
 	a.Append(&asm.Call{Label: "e"})
 	a.Append(&asm.Call{Label: "f"})
+	a.Append(&asm.Call{Label: "g"})
 	a.Append(&asm.StackFrameEnd{})
 	a.Append(&asm.Return{})
 
@@ -54,11 +57,13 @@ func TestAssembler(t *testing.T) {
 
 	d := &asm.Assembler{}
 	d.Append(&asm.Label{Name: "d"})
+	d.SetData("message", []byte("Hello"))
 	d.Append(&asm.MoveRegisterLabel{Destination: 0, Label: "a"})
 	d.Append(&asm.MoveRegisterLabel{Destination: 0, Label: "b"})
 	d.Append(&asm.MoveRegisterLabel{Destination: 0, Label: "c"})
 	d.Append(&asm.MoveRegisterLabel{Destination: 0, Label: "d"})
 	d.Append(&asm.MoveRegisterLabel{Destination: 0, Label: "e"})
+	d.Append(&asm.MoveRegisterLabel{Destination: 0, Label: "message"})
 	d.Append(&asm.MoveRegisterNumber{Destination: 0, Number: 123})
 	d.Append(&asm.MoveRegisterRegister{Destination: 0, Source: 1})
 	d.Append(&asm.Return{})
@@ -81,6 +86,18 @@ func TestAssembler(t *testing.T) {
 	f.Append(&asm.StackFrameEnd{FramePointer: true})
 	f.Append(&asm.Return{})
 
+	g := &asm.Assembler{}
+	g.Append(&asm.Label{Name: "g"})
+	g.Append(&asm.Call{Label: "a"})
+	g.Append(&asm.CompareRegisterRegister{SourceA: 0, SourceB: 1})
+	g.Append(&asm.Jump{Label: "a", Condition: token.Equal})
+	g.Append(&asm.Jump{Label: "a", Condition: token.NotEqual})
+	g.Append(&asm.Jump{Label: "a", Condition: token.Greater})
+	g.Append(&asm.Jump{Label: "a", Condition: token.GreaterEqual})
+	g.Append(&asm.Jump{Label: "a", Condition: token.Less})
+	g.Append(&asm.Jump{Label: "a", Condition: token.LessEqual})
+	g.Append(&asm.Return{})
+
 	final := asm.Assembler{}
 	final.Merge(a)
 	final.Merge(b)
@@ -88,6 +105,7 @@ func TestAssembler(t *testing.T) {
 	final.Merge(d)
 	final.Merge(e)
 	final.Merge(f)
+	final.Merge(g)
 
 	code, _, _ := final.Compile(&config.Build{Arch: config.ARM})
 	assert.NotNil(t, code)
diff --git a/src/asm/compilerARM.go b/src/asm/compilerARM.go
index 31f74c4..7601cf4 100644
--- a/src/asm/compilerARM.go
+++ b/src/asm/compilerARM.go
@@ -75,7 +75,20 @@ func (c *compilerARM) Compile(instr Instruction) {
 
 			offset := (address - patch.start) / 4
 
-			if offset != (offset & 0b11_11111111_11111111_11111111) {
+			var (
+				minOffset int
+				maxOffset int
+			)
+
+			if instr.Condition == token.Invalid {
+				minOffset = -(1 << 25)
+				maxOffset = (1 << 25) - 1
+			} else {
+				minOffset = -(1 << 18)
+				maxOffset = (1 << 18) - 1
+			}
+
+			if offset < minOffset || offset > maxOffset {
 				panic("not implemented: long jumps")
 			}
 
diff --git a/src/cpu/Register_test.go b/src/cpu/Register_test.go
index a7dd3d8..78eed90 100644
--- a/src/cpu/Register_test.go
+++ b/src/cpu/Register_test.go
@@ -8,6 +8,9 @@ import (
 )
 
 func TestRegisterString(t *testing.T) {
-	register := cpu.Register(1)
-	assert.Equal(t, "r1", register.String())
+	r1 := cpu.Register(1)
+	assert.Equal(t, r1.String(), "r1")
+
+	undefined := cpu.Register(-1)
+	assert.Equal(t, undefined.String(), "r?")
 }
\ No newline at end of file