diff --git a/core/ui/src/main/kotlin/app/aaps/core/ui/elements/DigitsKeyListenerWithComma.kt b/core/ui/src/main/kotlin/app/aaps/core/ui/elements/DigitsKeyListenerWithComma.kt
index fc7e1e2b5f..cd45f8320e 100644
--- a/core/ui/src/main/kotlin/app/aaps/core/ui/elements/DigitsKeyListenerWithComma.kt
+++ b/core/ui/src/main/kotlin/app/aaps/core/ui/elements/DigitsKeyListenerWithComma.kt
@@ -36,7 +36,7 @@ internal class DigitsKeyListenerWithComma @JvmOverloads constructor(private val
     override fun filter(
         source: CharSequence, start: Int, end: Int,
         dest: Spanned, dstart: Int, dend: Int
-    ): CharSequence {
+    ): CharSequence? {
         var sourceSequence = source
         var startIndex = start
         var endIndex = end