diff --git a/compiler/frontend/src/org/jetbrains/kotlin/cfg/pseudocode/PseudocodeImpl.kt b/compiler/frontend/src/org/jetbrains/kotlin/cfg/pseudocode/PseudocodeImpl.kt
index 1c3cc009daa..c4856c5f84f 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/cfg/pseudocode/PseudocodeImpl.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/cfg/pseudocode/PseudocodeImpl.kt
@@ -58,8 +58,12 @@ class PseudocodeImpl(override val correspondingElement: KtElement) : Pseudocode
         }
 
         fun resolveToInstruction(): Instruction {
-            assert(targetInstructionIndex != null)
-            return mutableInstructionList[targetInstructionIndex!!]
+            val index = targetInstructionIndex
+            if (index == null || index >= mutableInstructionList.size) {
+                error("resolveToInstruction: incorrect index $index for label $name " +
+                      "in subroutine ${correspondingElement.text} with instructions $mutableInstructionList")
+            }
+            return mutableInstructionList[index]
         }
 
         fun copy(newLabelIndex: Int): PseudocodeLabel {