diff --git a/idea/idea-completion/testData/basic/common/ClassRedeclaration2.kt b/idea/idea-completion/testData/basic/common/ClassRedeclaration2.kt
index 3432ee1fa20..a5f5d8569d0 100644
--- a/idea/idea-completion/testData/basic/common/ClassRedeclaration2.kt
+++ b/idea/idea-completion/testData/basic/common/ClassRedeclaration2.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 class A {
   fun f() : A
 }
diff --git a/idea/idea-completion/testData/basic/common/ObjectRedeclaration2.kt b/idea/idea-completion/testData/basic/common/ObjectRedeclaration2.kt
index 414eb30ff14..0c6cc1273f7 100644
--- a/idea/idea-completion/testData/basic/common/ObjectRedeclaration2.kt
+++ b/idea/idea-completion/testData/basic/common/ObjectRedeclaration2.kt
@@ -1,3 +1,5 @@
+// FIR_COMPARISON
+
 object A {
   fun f() : S
 }
diff --git a/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/util/declarationUtils.kt b/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/util/declarationUtils.kt
index 7d0095633e3..adafdeb38dc 100644
--- a/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/util/declarationUtils.kt
+++ b/idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/util/declarationUtils.kt
@@ -91,8 +91,12 @@ private fun KtDeclaration.findSourceNonLocalFirDeclarationByProvider(
                 firFile.declarations
             }
             val original = originalDeclaration
+
+            /*
+            It is possible that we will not be able to find needed declaration here when the code is invalid,
+            e.g, we have two conflicting declarations with the same name and we are searching in the wrong one
+             */
             declarations?.firstOrNull { it.psi == this || it.psi == original }
-                ?: error("Cannot find corresponding fir for\n${this.getElementTextInContext()}")
         }
         this is KtConstructor<*> -> {
             val containingClass = containingClassOrObject
diff --git a/idea/testData/resolve/references/InSecondClassObject.kt b/idea/testData/resolve/references/InSecondClassObject.kt
index 15beae7b6be..a6d2a2dd541 100644
--- a/idea/testData/resolve/references/InSecondClassObject.kt
+++ b/idea/testData/resolve/references/InSecondClassObject.kt
@@ -1,4 +1,3 @@
-// IGNORE_FIR
 package test
 
 class A