diff --git a/src/components/PaintControls.vue b/src/components/PaintControls.vue
index d2fe8cc54..166105f4c 100644
--- a/src/components/PaintControls.vue
+++ b/src/components/PaintControls.vue
@@ -134,10 +134,13 @@ export default defineComponent({
     });
 
     const setBrushColor = (color: string) => {
-      const hexa = `${color}FF`.toUpperCase();
-      if (hexa in hexToValue) {
-        paintStore.setBrushValue(hexToValue[hexa]);
+      const withAlpha = color.length === 9 ? color : `${color}FF`;
+      const hexa = withAlpha.toUpperCase();
+      const brushValue = hexToValue[hexa];
+      if (brushValue == null) {
+        throw new Error(`Brush value invalid`);
       }
+      paintStore.setBrushValue(brushValue);
     };
 
     const brushSize = computed(() => paintStore.brushSize);