diff --git a/src/arm/Add.go b/src/arm/Add.go
index be6d662..4cacfc0 100644
--- a/src/arm/Add.go
+++ b/src/arm/Add.go
@@ -4,10 +4,20 @@ import "git.urbach.dev/cli/q/src/cpu"
 
 // AddRegisterNumber adds a number to a register.
 func AddRegisterNumber(destination cpu.Register, source cpu.Register, number int) uint32 {
-	return addRegisterNumber(0b10, 0, destination, source, number)
+	return addRegisterNumber(destination, source, number, 0)
 }
 
 // AddRegisterRegister adds a register to a register.
 func AddRegisterRegister(destination cpu.Register, source cpu.Register, operand cpu.Register) uint32 {
-	return addRegisterRegister(0b10, 0, destination, source, operand)
+	return addRegisterRegister(destination, source, operand, 0)
+}
+
+// addRegisterNumber adds the register and optionally updates the condition flags based on the result.
+func addRegisterNumber(destination cpu.Register, source cpu.Register, number int, flags uint32) uint32 {
+	return flags<<29 | 0b100100010<<23 | reg2imm(destination, source, number)
+}
+
+// addRegisterRegister adds the registers and optionally updates the condition flags based on the result.
+func addRegisterRegister(destination cpu.Register, source cpu.Register, operand cpu.Register, flags uint32) uint32 {
+	return flags<<29 | 0b10001011000<<21 | reg3(destination, source, operand)
 }
diff --git a/src/arm/Compare.go b/src/arm/Compare.go
index 5bf7d1a..eb5a97e 100644
--- a/src/arm/Compare.go
+++ b/src/arm/Compare.go
@@ -4,10 +4,14 @@ import "git.urbach.dev/cli/q/src/cpu"
 
 // CompareRegisterNumber is an alias for a subtraction that updates the conditional flags and discards the result.
 func CompareRegisterNumber(register cpu.Register, number int) uint32 {
-	return addRegisterNumber(0b11, 1, ZR, register, number)
+	if number < 0 {
+		return addRegisterNumber(ZR, register, -number, 1)
+	}
+
+	return subRegisterNumber(ZR, register, number, 1)
 }
 
 // CompareRegisterRegister is an alias for a subtraction that updates the conditional flags and discards the result.
 func CompareRegisterRegister(reg1 cpu.Register, reg2 cpu.Register) uint32 {
-	return addRegisterRegister(0b11, 1, ZR, reg1, reg2)
+	return subRegisterRegister(ZR, reg1, reg2, 1)
 }
diff --git a/src/arm/Compare_test.go b/src/arm/Compare_test.go
index 7a3eca1..8224614 100644
--- a/src/arm/Compare_test.go
+++ b/src/arm/Compare_test.go
@@ -15,6 +15,7 @@ func TestCompareRegisterNumber(t *testing.T) {
 		Code   uint32
 	}{
 		{arm.X0, 1, 0xF100041F},
+		{arm.X0, -1, 0xB100041F},
 	}
 
 	for _, pattern := range usagePatterns {
diff --git a/src/arm/Sub.go b/src/arm/Sub.go
index 415db8d..bf84f50 100644
--- a/src/arm/Sub.go
+++ b/src/arm/Sub.go
@@ -4,10 +4,20 @@ import "git.urbach.dev/cli/q/src/cpu"
 
 // SubRegisterNumber subtracts a number from the given register.
 func SubRegisterNumber(destination cpu.Register, source cpu.Register, number int) uint32 {
-	return addRegisterNumber(0b11, 0, destination, source, number)
+	return subRegisterNumber(destination, source, number, 0)
 }
 
 // SubRegisterRegister subtracts a register from a register.
 func SubRegisterRegister(destination cpu.Register, source cpu.Register, operand cpu.Register) uint32 {
-	return addRegisterRegister(0b11, 0, destination, source, operand)
+	return subRegisterRegister(destination, source, operand, 0)
+}
+
+// subRegisterNumber subtracts the register and optionally updates the condition flags based on the result.
+func subRegisterNumber(destination cpu.Register, source cpu.Register, number int, flags uint32) uint32 {
+	return flags<<29 | 0b110100010<<23 | reg2imm(destination, source, number)
+}
+
+// subRegisterRegister subtracts the registers and optionally updates the condition flags based on the result.
+func subRegisterRegister(destination cpu.Register, source cpu.Register, operand cpu.Register, flags uint32) uint32 {
+	return flags<<29 | 0b11001011000<<21 | reg3(destination, source, operand)
 }
diff --git a/src/arm/encode.go b/src/arm/encode.go
index 767573d..38f968d 100644
--- a/src/arm/encode.go
+++ b/src/arm/encode.go
@@ -2,27 +2,19 @@ package arm
 
 import "git.urbach.dev/cli/q/src/cpu"
 
-// addRegisterNumber performs addition or subtraction on the given register
-// and optionally updates the condition flags based on the result.
-func addRegisterNumber(op uint32, flags uint32, destination cpu.Register, source cpu.Register, number int) uint32 {
-	number &= 0b1111_1111_1111
-	return op<<30 | flags<<29 | 0b100010<<23 | (uint32(number) << 10) | (uint32(source) << 5) | uint32(destination)
-}
-
-// addRegisterRegister performs addition or subtraction on the given registers
-// and optionally updates the condition flags based on the result.
-func addRegisterRegister(op uint32, flags uint32, destination cpu.Register, source cpu.Register, operand cpu.Register) uint32 {
-	return op<<30 | flags<<29 | 0b01011000<<21 | reg3(destination, source, operand)
-}
-
 // memory encodes an instruction with a register, a base register and an offset.
-func memory(destination cpu.Register, base cpu.Register, offset int) uint32 {
-	return uint32(offset&0b1_1111_1111)<<12 | uint32(base)<<5 | uint32(destination)
+func memory(destination cpu.Register, base cpu.Register, imm9 int) uint32 {
+	return uint32(imm9&0b1_1111_1111)<<12 | uint32(base)<<5 | uint32(destination)
 }
 
 // pair encodes an instruction using a register pair with memory.
-func pair(reg1 cpu.Register, reg2 cpu.Register, base cpu.Register, offset int) uint32 {
-	return uint32(offset&0b111_1111)<<15 | uint32(reg2)<<10 | uint32(base)<<5 | uint32(reg1)
+func pair(reg1 cpu.Register, reg2 cpu.Register, base cpu.Register, imm7 int) uint32 {
+	return uint32(imm7&0b111_1111)<<15 | uint32(reg2)<<10 | uint32(base)<<5 | uint32(reg1)
+}
+
+// reg2imm encodes an instruction with 2 registers and an immediate.
+func reg2imm(d cpu.Register, n cpu.Register, imm12 int) uint32 {
+	return uint32(imm12&0b1111_1111_1111)<<10 | uint32(n)<<5 | uint32(d)
 }
 
 // reg3 encodes an instruction with 3 registers.