diff --git a/analysis/analysis-internal-utils/src/org/jetbrains/kotlin/analysis/utils/errors/ExceptionAttachmentBuilder.kt b/analysis/analysis-internal-utils/src/org/jetbrains/kotlin/analysis/utils/errors/ExceptionAttachmentBuilder.kt
index 8c5d8e5688e..a6a513219b5 100644
--- a/analysis/analysis-internal-utils/src/org/jetbrains/kotlin/analysis/utils/errors/ExceptionAttachmentBuilder.kt
+++ b/analysis/analysis-internal-utils/src/org/jetbrains/kotlin/analysis/utils/errors/ExceptionAttachmentBuilder.kt
@@ -81,3 +81,16 @@ public inline fun checkWithAttachmentBuilder(
         buildErrorWithAttachment(message(), buildAttachment = buildAttachment)
     }
 }
+
+@OptIn(ExperimentalContracts::class)
+public inline fun requireWithAttachmentBuilder(
+    condition: Boolean,
+    message: () -> String,
+    buildAttachment: ExceptionAttachmentBuilder.() -> Unit = {}
+) {
+    contract { returns() implies (condition) }
+
+    if (!condition) {
+        buildErrorWithAttachment(message(), buildAttachment = buildAttachment)
+    }
+}
diff --git a/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/providers/LLFirProviderHelper.kt b/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/providers/LLFirProviderHelper.kt
index 630c49812cf..9abe6251b75 100644
--- a/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/providers/LLFirProviderHelper.kt
+++ b/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/providers/LLFirProviderHelper.kt
@@ -42,11 +42,7 @@ internal class LLFirProviderHelper(
             ?: return@createCache null
         if (ktClass.getClassId() == null) return@createCache null
         val firFile = firFileBuilder.buildRawFirFileWithCaching(ktClass.containingKtFile)
-        FirElementFinder.findElementIn<FirClassLikeDeclaration>(
-            firFile,
-            canGoInside = { it is FirRegularClass },
-            predicate = { it.symbol.classId == classId },
-        )
+        FirElementFinder.findClassifierWithClassId(firFile, classId)
             ?: error("Classifier $classId was found in file ${ktClass.containingKtFile.virtualFilePath} but was not found in FirFile")
     }
 
diff --git a/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/util/FirNonLocalDeclarationSearcher.kt b/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/util/FirNonLocalDeclarationSearcher.kt
index 32b1c60bfb0..c4aeb7f912e 100644
--- a/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/util/FirNonLocalDeclarationSearcher.kt
+++ b/analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/util/FirNonLocalDeclarationSearcher.kt
@@ -5,15 +5,55 @@
 
 package org.jetbrains.kotlin.analysis.low.level.api.fir.util
 
+import org.jetbrains.kotlin.analysis.utils.errors.requireWithAttachmentBuilder
 import org.jetbrains.kotlin.fir.FirElement
+import org.jetbrains.kotlin.fir.declarations.FirClassLikeDeclaration
+import org.jetbrains.kotlin.fir.declarations.FirDeclaration
 import org.jetbrains.kotlin.fir.declarations.FirFile
 import org.jetbrains.kotlin.fir.declarations.FirRegularClass
 import org.jetbrains.kotlin.fir.declarations.utils.classId
+import org.jetbrains.kotlin.fir.packageFqName
 import org.jetbrains.kotlin.fir.render
 import org.jetbrains.kotlin.fir.visitors.FirVisitorVoid
-import org.jetbrains.kotlin.psi.KtElement
+import org.jetbrains.kotlin.name.ClassId
 
 object FirElementFinder {
+    fun findClassifierWithClassId(firFile: FirFile, classId: ClassId): FirClassLikeDeclaration? {
+        requireWithAttachmentBuilder(!classId.isLocal, { "ClassId should not be local" }) {
+            withEntry("classId", classId) { it.asString() }
+        }
+        requireWithAttachmentBuilder(
+            firFile.packageFqName == classId.packageFqName,
+            { "ClassId should not be local" }
+        ) {
+            withEntry("FirFile.packageName", firFile.packageFqName) { it.asString() }
+            withEntry("ClassId.packageName", classId.packageFqName) { it.asString() }
+        }
+
+        val classIdPathSegment = classId.relativeClassName.pathSegments()
+        var result: FirClassLikeDeclaration? = null
+
+        fun find(declarations: List<FirDeclaration>, classIdPathIndex: Int) {
+            if (result != null) return
+            val currentClassSegment = classIdPathSegment[classIdPathIndex]
+
+            for (subDeclaration in declarations) {
+                if (subDeclaration is FirClassLikeDeclaration && currentClassSegment == subDeclaration.symbol.name) {
+                    if (classIdPathIndex == classIdPathSegment.lastIndex) {
+                        result = subDeclaration
+                        return
+                    }
+                    if (subDeclaration is FirRegularClass) {
+                        find(subDeclaration.declarations, classIdPathIndex + 1)
+                    }
+                }
+            }
+        }
+
+        find(firFile.declarations, classIdPathIndex = 0)
+        return result
+    }
+
     inline fun <reified E : FirElement> findElementIn(
         container: FirElement,
         crossinline canGoInside: (E) -> Boolean = { true },