diff --git a/idea/src/org/jetbrains/kotlin/idea/debugger/KotlinFrameExtraVariablesProvider.kt b/idea/src/org/jetbrains/kotlin/idea/debugger/KotlinFrameExtraVariablesProvider.kt
index 7074de4d380..e0a15e0df67 100644
--- a/idea/src/org/jetbrains/kotlin/idea/debugger/KotlinFrameExtraVariablesProvider.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/debugger/KotlinFrameExtraVariablesProvider.kt
@@ -40,18 +40,14 @@ import java.util.LinkedHashSet
 import org.jetbrains.kotlin.idea.caches.resolve.analyzeFully
 
 public class KotlinFrameExtraVariablesProvider : FrameExtraVariablesProvider {
-    override fun isAvailable(sourcePosition: SourcePosition?, evalContext: EvaluationContext?): Boolean {
-        if (sourcePosition == null) return false
+    override fun isAvailable(sourcePosition: SourcePosition, evalContext: EvaluationContext): Boolean {
         if (sourcePosition.getLine() < 0) return false
         return sourcePosition.getFile().getFileType() == KotlinFileType.INSTANCE && DebuggerSettings.getInstance().AUTO_VARIABLES_MODE
     }
 
-    override fun collectVariables(sourcePosition: SourcePosition?, evalContext: EvaluationContext?, alreadyCollected: Set<String>?
-    ): Set<TextWithImports>? {
-        if (sourcePosition != null) {
-            return runReadAction { findAdditionalExpressions(sourcePosition) }
-        }
-        return setOf()
+    override fun collectVariables(
+            sourcePosition: SourcePosition, evalContext: EvaluationContext, alreadyCollected: MutableSet<String>): Set<TextWithImports> {
+        return runReadAction { findAdditionalExpressions(sourcePosition) }
     }
 }
 
diff --git a/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/AbstractKotlinEvaluateExpressionTest.kt b/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/AbstractKotlinEvaluateExpressionTest.kt
index d056b7c62b8..014d60dc172 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/AbstractKotlinEvaluateExpressionTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/AbstractKotlinEvaluateExpressionTest.kt
@@ -223,7 +223,7 @@ public abstract class AbstractKotlinEvaluateExpressionTest : KotlinDebuggerTestB
     }
 
     fun getExtraVars(): Set<TextWithImports> {
-        return KotlinFrameExtraVariablesProvider().collectVariables(debuggerContext!!.getSourcePosition(), evaluationContext, hashSetOf())!!
+        return KotlinFrameExtraVariablesProvider().collectVariables(debuggerContext!!.getSourcePosition(), evaluationContext!!, hashSetOf())!!
     }
 
     private inner class Printer() {