diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/RangeCodegenUtil.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/RangeCodegenUtil.java
index 9e9d0385a04..8f17fcc17c9 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/RangeCodegenUtil.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/RangeCodegenUtil.java
@@ -19,11 +19,11 @@ package org.jetbrains.kotlin.codegen;
 import com.google.common.collect.ImmutableMap;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.jetbrains.kotlin.builtins.KotlinBuiltIns;
 import org.jetbrains.kotlin.builtins.PrimitiveType;
 import org.jetbrains.kotlin.descriptors.CallableDescriptor;
 import org.jetbrains.kotlin.descriptors.ClassifierDescriptor;
 import org.jetbrains.kotlin.name.FqName;
+import org.jetbrains.kotlin.name.FqNameUnsafe;
 import org.jetbrains.kotlin.name.Name;
 import org.jetbrains.kotlin.psi.*;
 import org.jetbrains.kotlin.resolve.DescriptorUtils;
@@ -107,7 +107,10 @@ public class RangeCodegenUtil {
             @NotNull ImmutableMap<FqName, PrimitiveType> map
     ) {
         ClassifierDescriptor declarationDescriptor = rangeOrProgression.getConstructor().getDeclarationDescriptor();
-        return declarationDescriptor == null ? null : map.get(DescriptorUtils.getFqNameSafe(declarationDescriptor));
+        if (declarationDescriptor == null) return null;
+        FqNameUnsafe fqName = DescriptorUtils.getFqName(declarationDescriptor);
+        if (!fqName.isSafe()) return null;
+        return map.get(fqName.toSafe());
     }
 
     @Nullable