diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/api/SequenceArbitrary.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/api/SequenceArbitrary.kt
index 31d1abe87..80172f7cc 100644
--- a/kotlin/src/main/kotlin/net/jqwik/kotlin/api/SequenceArbitrary.kt
+++ b/kotlin/src/main/kotlin/net/jqwik/kotlin/api/SequenceArbitrary.kt
@@ -21,7 +21,7 @@ class SequenceArbitrary<T>(elementArbitrary: Arbitrary<T>) : ArbitraryDecorator<
     private var listArbitrary: ListArbitrary<T>
 
     init {
-        this.listArbitrary = elementArbitrary.list()
+        this.listArbitrary = elementArbitrary.list() as ListArbitrary<T>
     }
 
     override fun arbitrary(): Arbitrary<Sequence<T>> {
diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/api/StringArbitraryExtensions.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/api/StringArbitraryExtensions.kt
index 2c5ceb4c7..61ebeb101 100644
--- a/kotlin/src/main/kotlin/net/jqwik/kotlin/api/StringArbitraryExtensions.kt
+++ b/kotlin/src/main/kotlin/net/jqwik/kotlin/api/StringArbitraryExtensions.kt
@@ -7,4 +7,4 @@ import org.apiguardian.api.API
  * Set the minimum and maximum allowed length of generated strings.
  */
 @API(status = API.Status.EXPERIMENTAL, since = "1.6.0")
-fun StringArbitrary.ofLength(range: IntRange) = ofMinLength(range.first).ofMaxLength(range.last)
\ No newline at end of file
+fun StringArbitrary.ofLength(range: IntRange): StringArbitrary = ofMinLength(range.first).ofMaxLength(range.last)
\ No newline at end of file