diff --git a/idea/idea-fir/build.gradle.kts b/idea/idea-fir/build.gradle.kts
index f477027cab8..32dde68768c 100644
--- a/idea/idea-fir/build.gradle.kts
+++ b/idea/idea-fir/build.gradle.kts
@@ -30,7 +30,7 @@ dependencies {
 }
 
 sourceSets {
-    "main" { none() }
+    "main" { projectDefault() }
     "test" { projectDefault() }
 }
 
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/HighlightingUtils.kt b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/HighlightingUtils.kt
similarity index 98%
rename from idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/HighlightingUtils.kt
rename to idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/HighlightingUtils.kt
index 2eb432c14a9..8c8d7fa45c7 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/HighlightingUtils.kt
+++ b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/HighlightingUtils.kt
@@ -3,7 +3,7 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package org.jetbrains.kotlin.idea.highlighter
+package org.jetbrains.kotlin.idea.fir.highlighter
 
 import com.intellij.lang.jvm.JvmModifier
 import com.intellij.openapi.editor.colors.TextAttributesKey
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/KotlinFirPsiChecker.kt b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/KotlinFirPsiChecker.kt
similarity index 88%
rename from idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/KotlinFirPsiChecker.kt
rename to idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/KotlinFirPsiChecker.kt
index 4320950886f..588f7669d85 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/KotlinFirPsiChecker.kt
+++ b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/KotlinFirPsiChecker.kt
@@ -3,14 +3,17 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package org.jetbrains.kotlin.idea.highlighter
+package org.jetbrains.kotlin.idea.fir.highlighter
 
 import com.intellij.lang.annotation.AnnotationHolder
 import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.diagnostics.Diagnostic
+import org.jetbrains.kotlin.idea.fir.highlighter.visitors.FirAfterResolveHighlightingVisitor
 import org.jetbrains.kotlin.idea.frontend.api.FrontendAnalysisSession
 import org.jetbrains.kotlin.idea.frontend.api.fir.AnalysisSessionFirImpl
-import org.jetbrains.kotlin.idea.highlighter.visitors.FirAfterResolveHighlightingVisitor
+import org.jetbrains.kotlin.idea.highlighter.AbstractKotlinPsiChecker
+import org.jetbrains.kotlin.idea.highlighter.Diagnostic2Annotation
+import org.jetbrains.kotlin.idea.highlighter.IdeErrorMessages
 import org.jetbrains.kotlin.psi.KtElement
 import org.jetbrains.kotlin.psi.KtFile
 
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/DeclarationHighlightingVisitor.kt b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/DeclarationHighlightingVisitor.kt
similarity index 87%
rename from idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/DeclarationHighlightingVisitor.kt
rename to idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/DeclarationHighlightingVisitor.kt
index d1ba27b6ad5..c797ec0b695 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/DeclarationHighlightingVisitor.kt
+++ b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/DeclarationHighlightingVisitor.kt
@@ -3,10 +3,13 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package org.jetbrains.kotlin.idea.highlighter.visitors
+package org.jetbrains.kotlin.idea.fir.highlighter.visitors
 
 import com.intellij.lang.annotation.AnnotationHolder
 import com.intellij.psi.util.PsiUtilCore
+import org.jetbrains.kotlin.idea.fir.highlighter.textAttributesForClass
+import org.jetbrains.kotlin.idea.fir.highlighter.textAttributesForKtParameterDeclaration
+import org.jetbrains.kotlin.idea.fir.highlighter.textAttributesForKtPropertyDeclaration
 import org.jetbrains.kotlin.idea.highlighter.*
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/ExpressionsSmartcastHighlightingVisitor.kt b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/ExpressionsSmartcastHighlightingVisitor.kt
similarity index 97%
rename from idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/ExpressionsSmartcastHighlightingVisitor.kt
rename to idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/ExpressionsSmartcastHighlightingVisitor.kt
index 53f1574c9bd..7099a0c64bf 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/ExpressionsSmartcastHighlightingVisitor.kt
+++ b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/ExpressionsSmartcastHighlightingVisitor.kt
@@ -3,7 +3,7 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package org.jetbrains.kotlin.idea.highlighter.visitors
+package org.jetbrains.kotlin.idea.fir.highlighter.visitors
 
 import com.intellij.lang.annotation.AnnotationHolder
 import com.intellij.psi.PsiElement
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/FirAfterResolveHighlightingVisitor.kt b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/FirAfterResolveHighlightingVisitor.kt
similarity index 94%
rename from idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/FirAfterResolveHighlightingVisitor.kt
rename to idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/FirAfterResolveHighlightingVisitor.kt
index b3a38afce96..8ced5481e97 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/FirAfterResolveHighlightingVisitor.kt
+++ b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/FirAfterResolveHighlightingVisitor.kt
@@ -3,7 +3,7 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package org.jetbrains.kotlin.idea.highlighter.visitors
+package org.jetbrains.kotlin.idea.fir.highlighter.visitors
 
 import com.intellij.lang.annotation.AnnotationHolder
 import org.jetbrains.kotlin.idea.frontend.api.FrontendAnalysisSession
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/FunctionCallHighlightingVisitor.kt b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/FunctionCallHighlightingVisitor.kt
similarity index 96%
rename from idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/FunctionCallHighlightingVisitor.kt
rename to idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/FunctionCallHighlightingVisitor.kt
index 52af8cbb5a1..1580ca5817d 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/FunctionCallHighlightingVisitor.kt
+++ b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/FunctionCallHighlightingVisitor.kt
@@ -3,7 +3,7 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package org.jetbrains.kotlin.idea.highlighter.visitors
+package org.jetbrains.kotlin.idea.fir.highlighter.visitors
 
 import com.intellij.lang.annotation.AnnotationHolder
 import com.intellij.openapi.editor.colors.TextAttributesKey
@@ -12,7 +12,6 @@ import org.jetbrains.kotlin.idea.refactoring.fqName.getKotlinFqName
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.isExtensionDeclaration
-import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameOrNull
 import org.jetbrains.kotlin.serialization.deserialization.KOTLIN_SUSPEND_BUILT_IN_FUNCTION_FQ_NAME
 import org.jetbrains.kotlin.idea.highlighter.KotlinHighlightingColors as Colors
 
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/TypeHighlightingVisitor.kt b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/TypeHighlightingVisitor.kt
similarity index 93%
rename from idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/TypeHighlightingVisitor.kt
rename to idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/TypeHighlightingVisitor.kt
index a362e092a9c..8db343e445e 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/TypeHighlightingVisitor.kt
+++ b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/TypeHighlightingVisitor.kt
@@ -3,16 +3,16 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package org.jetbrains.kotlin.idea.highlighter.visitors
+package org.jetbrains.kotlin.idea.fir.highlighter.visitors
 
 import com.intellij.lang.annotation.AnnotationHolder
 import com.intellij.openapi.util.TextRange
 import com.intellij.psi.PsiElement
 import com.intellij.psi.util.PsiTreeUtil
+import org.jetbrains.kotlin.idea.fir.highlighter.isAnnotationClass
+import org.jetbrains.kotlin.idea.fir.highlighter.textAttributesKeyForTypeDeclaration
 import org.jetbrains.kotlin.idea.frontend.api.FrontendAnalysisSession
 import org.jetbrains.kotlin.idea.highlighter.NameHighlighter
-import org.jetbrains.kotlin.idea.highlighter.isAnnotationClass
-import org.jetbrains.kotlin.idea.highlighter.textAttributesKeyForTypeDeclaration
 import org.jetbrains.kotlin.idea.references.mainReference
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.idea.highlighter.KotlinHighlightingColors as Colors
diff --git a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/VariableReferenceHighlightingVisitor.kt b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/VariableReferenceHighlightingVisitor.kt
similarity index 95%
rename from idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/VariableReferenceHighlightingVisitor.kt
rename to idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/VariableReferenceHighlightingVisitor.kt
index 9a560f67a07..c1319ef2578 100644
--- a/idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/highlighter/visitors/VariableReferenceHighlightingVisitor.kt
+++ b/idea/idea-fir/src/org/jetbrains/kotlin/idea/fir/highlighter/visitors/VariableReferenceHighlightingVisitor.kt
@@ -3,7 +3,7 @@
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
-package org.jetbrains.kotlin.idea.highlighter.visitors
+package org.jetbrains.kotlin.idea.fir.highlighter.visitors
 
 import com.intellij.lang.annotation.AnnotationHolder
 import com.intellij.psi.PsiElement
@@ -13,9 +13,9 @@ import com.intellij.psi.PsiVariable
 import com.intellij.psi.util.PsiUtilCore
 import com.intellij.psi.util.parentOfType
 import org.jetbrains.kotlin.idea.KotlinIdeaAnalysisBundle
+import org.jetbrains.kotlin.idea.fir.highlighter.textAttributesKeyForPropertyDeclaration
 import org.jetbrains.kotlin.idea.frontend.api.FrontendAnalysisSession
 import org.jetbrains.kotlin.idea.highlighter.NameHighlighter
-import org.jetbrains.kotlin.idea.highlighter.textAttributesKeyForPropertyDeclaration
 import org.jetbrains.kotlin.idea.references.mainReference
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
diff --git a/idea/resources-fir/META-INF/plugin.xml b/idea/resources-fir/META-INF/plugin.xml
index 6375eea4dc6..f99ae30b6b4 100644
--- a/idea/resources-fir/META-INF/plugin.xml
+++ b/idea/resources-fir/META-INF/plugin.xml
@@ -74,7 +74,7 @@ The Kotlin FIR plugin provides language support in IntelliJ IDEA and Android Stu
   <!--  </extensions>-->
 
   <extensions defaultExtensionNs="org.jetbrains.kotlin">
-    <beforeResolveHighlightingVisitor implementation="org.jetbrains.kotlin.idea.highlighter.visitors.DeclarationHighlightingExtension"/>
+    <beforeResolveHighlightingVisitor implementation="org.jetbrains.kotlin.idea.fir.highlighter.visitors.DeclarationHighlightingExtension"/>
   </extensions>
 
 
@@ -90,8 +90,8 @@ The Kotlin FIR plugin provides language support in IntelliJ IDEA and Android Stu
     <applicationService serviceInterface="org.jetbrains.kotlin.idea.references.KotlinReferenceProviderContributor"
                         serviceImplementation="org.jetbrains.kotlin.idea.references.KotlinFirReferenceContributor"/>
     <applicationService serviceImplementation="org.jetbrains.kotlin.idea.PluginStartupService"/>
-    <highlightRangeExtension implementation="org.jetbrains.kotlin.idea.highlighter.KotlinFirPsiChecker"/>
-    <annotator language="kotlin" implementationClass="org.jetbrains.kotlin.idea.highlighter.KotlinFirPsiChecker"/>
+    <highlightRangeExtension implementation="org.jetbrains.kotlin.idea.fir.highlighter.KotlinFirPsiChecker"/>
+    <annotator language="kotlin" implementationClass="org.jetbrains.kotlin.idea.fir.highlighter.KotlinFirPsiChecker"/>
     <projectService serviceInterface="org.jetbrains.kotlin.idea.fir.low.level.api.FirIdeResolveStateService"
                     serviceImplementation="org.jetbrains.kotlin.idea.fir.low.level.api.FirIdeResolveStateServiceImpl"/>
     <projectService serviceImplementation="org.jetbrains.kotlin.resolve.jvm.KotlinJavaPsiFacade"/>