diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/DefaultConstructorMarkerProvider.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/DefaultConstructorMarkerProvider.kt
index dbb12d62a..fc903cb02 100644
--- a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/DefaultConstructorMarkerProvider.kt
+++ b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/DefaultConstructorMarkerProvider.kt
@@ -4,7 +4,6 @@ import net.jqwik.api.Arbitraries
 import net.jqwik.api.Arbitrary
 import net.jqwik.api.providers.ArbitraryProvider
 import net.jqwik.api.providers.TypeUsage
-import net.jqwik.kotlin.api.IntRangeArbitrary
 import kotlin.jvm.internal.DefaultConstructorMarker
 
 class DefaultConstructorMarkerProvider: ArbitraryProvider {
diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinReflectionSupport.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinReflectionSupport.kt
index 9d90e6cf3..ccfd1f2df 100644
--- a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinReflectionSupport.kt
+++ b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinReflectionSupport.kt
@@ -31,7 +31,7 @@ val Parameter.kotlinParameter: KParameter?
             // A generated parameter e.g. DefaultConstructorMarker
             return null
         }
-        return parameters.get(kotlinIndex)
+        return parameters[kotlinIndex]
     }
 
 private fun Parameter.isSuspendFunctionContinuationParameter() =
diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinSizeConfigurator.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinSizeConfigurator.kt
index 10ded0165..22a09e242 100644
--- a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinSizeConfigurator.kt
+++ b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinSizeConfigurator.kt
@@ -11,6 +11,7 @@ class KotlinIntRangeConfigurator : ArbitraryConfiguratorBase() {
         return targetType.isAssignableFrom(IntRange::class.java)
     }
 
+    @Suppress("unused") // Used by jqwik
     fun configure(arbitrary: Arbitrary<IntRange>, range: JqwikIntRange): Arbitrary<IntRange> {
         return if (arbitrary is IntRangeArbitrary) {
             arbitrary.between(range.min, range.max)
diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinUniqueElementsConfigurator.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinUniqueElementsConfigurator.kt
index 9dda1ea8e..6a764ded0 100644
--- a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinUniqueElementsConfigurator.kt
+++ b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/KotlinUniqueElementsConfigurator.kt
@@ -11,7 +11,7 @@ import net.jqwik.kotlin.api.isAssignableFrom
 import java.util.function.Function
 
 class KotlinUniqueElementsConfigurator : ArbitraryConfigurator {
-    @Suppress("UNCHECKED_CAST")
+    @Suppress("UNCHECKED_CAST", "WRONG_NULLABILITY_FOR_JAVA_OVERRIDE")
     override fun <T> configure(arbitrary: Arbitrary<T>, targetType: TypeUsage): Arbitrary<T> {
         return targetType.findAnnotation(UniqueElements::class.java).map { uniqueness ->
             return@map when {
@@ -21,7 +21,7 @@ class KotlinUniqueElementsConfigurator : ArbitraryConfigurator {
                     sequenceArbitrary.filter {
                         isUnique(
                             it.toList(),
-                            extractor<T>(uniqueness) as Function<Any?, Any>
+                            extractor(uniqueness) as Function<Any?, Any>
                         )
                     }
                 }
@@ -40,11 +40,11 @@ class KotlinUniqueElementsConfigurator : ArbitraryConfigurator {
         arbitrary: SequenceArbitrary<T>,
         uniqueness: UniqueElements
     ): SequenceArbitrary<T> {
-        val extractor = extractor<T>(uniqueness) as Function<T?, *>
+        val extractor = extractor(uniqueness) as Function<T?, *>
         return arbitrary.uniqueElements(extractor)
     }
 
-    private fun <T> extractor(uniqueElements: UniqueElements): Function<*, *> {
+    private fun extractor(uniqueElements: UniqueElements): Function<*, *> {
         val extractorClass: Class<out Function<*, *>> = uniqueElements.by.java
         return if (extractorClass == NOT_SET::class.java) Function.identity<Any>()
         // TODO: Create instance in context of test instance.
diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/PairReportingFormat.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/PairReportingFormat.kt
index a64b29072..5bbf46e75 100644
--- a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/PairReportingFormat.kt
+++ b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/PairReportingFormat.kt
@@ -9,6 +9,7 @@ class PairReportingFormat : SampleReportingFormat {
         return value is Pair<*, *>
     }
 
+    @Suppress("NULLABILITY_MISMATCH_BASED_ON_JAVA_ANNOTATIONS")
     override fun report(value: Any): Any {
         val pair = value as Pair<*, *>
         return Tuple.of(pair.first, pair.second)
diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/SuspendedPropertyMethodsHook.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/SuspendedPropertyMethodsHook.kt
index c417c0ca3..33b017ab8 100644
--- a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/SuspendedPropertyMethodsHook.kt
+++ b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/SuspendedPropertyMethodsHook.kt
@@ -20,7 +20,7 @@ class SuspendedPropertyMethodsHook : ResolveParameterHook, InvokePropertyMethodH
 
     override fun propagateTo(): PropagationMode = PropagationMode.ALL_DESCENDANTS
 
-    override fun appliesTo(element: Optional<AnnotatedElement>) =
+    override fun appliesTo(element: Optional<AnnotatedElement>): Boolean =
         element.map { e -> e.isSuspendFunction() }.orElse(false)
 
     @Suppress("UNCHECKED_CAST")
diff --git a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/TripleReportingFormat.kt b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/TripleReportingFormat.kt
index 9ebb283dc..a3bd346a8 100644
--- a/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/TripleReportingFormat.kt
+++ b/kotlin/src/main/kotlin/net/jqwik/kotlin/internal/TripleReportingFormat.kt
@@ -9,6 +9,7 @@ class TripleReportingFormat : SampleReportingFormat {
         return value is Triple<*, *, *>
     }
 
+    @Suppress("NULLABILITY_MISMATCH_BASED_ON_JAVA_ANNOTATIONS")
     override fun report(value: Any): Any {
         val triple = value as Triple<*, *, *>
         return Tuple.of(triple.first, triple.second, triple.third)