diff --git a/backend/colour.go b/backend/colour.go
new file mode 100644
index 0000000..0886ad4
--- /dev/null
+++ b/backend/colour.go
@@ -0,0 +1,30 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+)
+
+func ConvertStringToColour(colourStr string) (int, error) {
+	if len(colourStr) == 0 {
+		return 0xFF0000, nil // Default colour if no string is provided
+	}
+	if colourStr[0] == '#' {
+		colourStr = colourStr[1:]
+	}
+	if len(colourStr) != 6 && len(colourStr) != 3 {
+		return 0, errors.New("colour must be a valid hex string")
+	}
+	var colour int
+	_, err := fmt.Sscanf(colourStr, "%x", &colour)
+	if err != nil {
+		return 0, fmt.Errorf("invalid colour format: %v", err)
+	}
+	if len(colourStr) == 3 {
+		r := (colour & 0xF00) >> 8
+		g := (colour & 0x0F0) >> 4
+		b := (colour & 0x00F) >> 0
+		colour = (r << 16 << 4) | (g << 8 << 4) | (b << 0 << 4)
+	}
+	return colour, nil
+}
diff --git a/backend/colour_test.go b/backend/colour_test.go
new file mode 100644
index 0000000..812e8bc
--- /dev/null
+++ b/backend/colour_test.go
@@ -0,0 +1,30 @@
+package main
+
+import (
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+func TestConvertStringToColourWithSign(t *testing.T) {
+	colour, err := ConvertStringToColour("#123456")
+	require.NoError(t, err)
+	require.Equal(t, 0x123456, colour)
+}
+
+func TestConvertStringToColourWithoutSign(t *testing.T) {
+	colour, err := ConvertStringToColour("123456")
+	require.NoError(t, err)
+	require.Equal(t, 0x123456, colour)
+}
+
+func TestConvertStringToColourWithSignThreeDigits(t *testing.T) {
+	colour, err := ConvertStringToColour("#ABC")
+	require.NoError(t, err)
+	require.Equal(t, 0xA0B0C0, colour)
+}
+
+func TestConvertStringToColourWithoutSignThreeDigits(t *testing.T) {
+	colour, err := ConvertStringToColour("ABC")
+	require.NoError(t, err)
+	require.Equal(t, 0xA0B0C0, colour)
+}
diff --git a/backend/db.go b/backend/db.go
index 0c58a85..151594d 100644
--- a/backend/db.go
+++ b/backend/db.go
@@ -127,23 +127,6 @@ func (db *Db) GetUserAllowanceById(userId int, allowanceId int) (*Allowance, err
 	return allowance, nil
 }
 
-func ConvertStringToColour(colourStr string) (int, error) {
-	if len(colourStr) == 0 {
-		return 0xFF0000, nil // Default colour if no string is provided
-	}
-	if colourStr[0] == '#' {
-		colourStr = colourStr[1:]
-	}
-	if len(colourStr) != 6 && len(colourStr) != 3 {
-		return 0, errors.New("colour must be a valid hex string")
-	}
-	colour, err := fmt.Sscanf(colourStr, "%x", &colourStr)
-	if err != nil {
-		return 0, fmt.Errorf("invalid colour format: %v", err)
-	}
-	return colour, nil
-}
-
 func (db *Db) CreateAllowance(userId int, allowance *CreateAllowanceRequest) (int, error) {
 	// Check if user exists before attempting to create an allowance
 	exists, err := db.UserExists(userId)
@@ -287,7 +270,7 @@ func (db *Db) UpdateAllowance(userId int, allowanceId int, allowance *UpdateAllo
 
 	target := int(math.Round(allowance.Target * 100.0))
 	err = tx.Query("update allowances set name=?, target=?, weight=?, colour=? where id = ? and user_id = ?").
-		Bind(allowance.Name, target, allowance.Weight, allowanceId, userId, colour).
+		Bind(allowance.Name, target, allowance.Weight, colour, allowanceId, userId).
 		Exec()
 	if err != nil {
 		return err