diff --git a/compiler/testData/diagnostics/tests/funInterface/basicFunInterface.txt b/compiler/testData/diagnostics/tests/funInterface/basicFunInterface.txt
index fb435025835..fb451d3fc1a 100644
--- a/compiler/testData/diagnostics/tests/funInterface/basicFunInterface.txt
+++ b/compiler/testData/diagnostics/tests/funInterface/basicFunInterface.txt
@@ -1,6 +1,6 @@
 package
 
-public interface Foo {
+public fun interface Foo {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public abstract fun invoke(): kotlin.Unit
diff --git a/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceConversion.txt b/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceConversion.txt
index 54f2013b6c4..d38d03069da 100644
--- a/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceConversion.txt
+++ b/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceConversion.txt
@@ -3,7 +3,7 @@ package
 public fun foo(/*0*/ f: Foo): kotlin.Unit
 public fun test(): kotlin.Unit
 
-public interface Foo {
+public fun interface Foo {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public abstract fun invoke(): kotlin.Unit
diff --git a/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceDisabled.txt b/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceDisabled.txt
index fb435025835..fb451d3fc1a 100644
--- a/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceDisabled.txt
+++ b/compiler/testData/diagnostics/tests/funInterface/basicFunInterfaceDisabled.txt
@@ -1,6 +1,6 @@
 package
 
-public interface Foo {
+public fun interface Foo {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public abstract fun invoke(): kotlin.Unit
diff --git a/compiler/testData/diagnostics/tests/funInterface/funInterfaceSyntheticConstructors.txt b/compiler/testData/diagnostics/tests/funInterface/funInterfaceSyntheticConstructors.txt
index 6f55a69343d..1926f4c074f 100644
--- a/compiler/testData/diagnostics/tests/funInterface/funInterfaceSyntheticConstructors.txt
+++ b/compiler/testData/diagnostics/tests/funInterface/funInterfaceSyntheticConstructors.txt
@@ -3,7 +3,7 @@ package
 public fun foo(/*0*/ f: KRunnable): kotlin.Unit
 public fun test(): kotlin.Unit
 
-public interface KRunnable {
+public fun interface KRunnable {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public abstract fun invoke(): kotlin.Unit
diff --git a/compiler/testData/diagnostics/tests/funInterface/genericSubstitutionForFunInterface.txt b/compiler/testData/diagnostics/tests/funInterface/genericSubstitutionForFunInterface.txt
index 7e20b13b3cf..026c67a3d5a 100644
--- a/compiler/testData/diagnostics/tests/funInterface/genericSubstitutionForFunInterface.txt
+++ b/compiler/testData/diagnostics/tests/funInterface/genericSubstitutionForFunInterface.txt
@@ -2,7 +2,7 @@ package
 
 public fun test(/*0*/ k: K<kotlin.String>, /*1*/ f_string: F<kotlin.String>, /*2*/ f_int: F<kotlin.Int>, /*3*/ f_pr: F<PR<kotlin.String, kotlin.Int>>): kotlin.Unit
 
-public interface F</*0*/ S> {
+public fun interface F</*0*/ S> {
     public abstract fun apply(/*0*/ s: S): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
diff --git a/compiler/testData/diagnostics/tests/funInterface/severalConversionsForFunInterface.txt b/compiler/testData/diagnostics/tests/funInterface/severalConversionsForFunInterface.txt
index 5bd556848f2..c767c1251b1 100644
--- a/compiler/testData/diagnostics/tests/funInterface/severalConversionsForFunInterface.txt
+++ b/compiler/testData/diagnostics/tests/funInterface/severalConversionsForFunInterface.txt
@@ -11,7 +11,7 @@ public interface J {
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
 
-public interface KRunnable {
+public fun interface KRunnable {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public abstract fun run(): kotlin.Unit
diff --git a/compiler/testData/diagnostics/tests/funInterface/suspendFunInterfaceConversion.txt b/compiler/testData/diagnostics/tests/funInterface/suspendFunInterfaceConversion.txt
index e0b84d4ad8b..a5aac0270cb 100644
--- a/compiler/testData/diagnostics/tests/funInterface/suspendFunInterfaceConversion.txt
+++ b/compiler/testData/diagnostics/tests/funInterface/suspendFunInterfaceConversion.txt
@@ -4,7 +4,7 @@ public suspend fun bar(): kotlin.Unit
 public fun run(/*0*/ r: SuspendRunnable): kotlin.Unit
 public fun test(): kotlin.Unit
 
-public interface SuspendRunnable {
+public fun interface SuspendRunnable {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public abstract suspend fun invoke(): kotlin.Unit
diff --git a/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRenderer.kt b/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRenderer.kt
index a3f14910fff..3d5e1ceb257 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRenderer.kt
+++ b/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRenderer.kt
@@ -303,6 +303,7 @@ enum class DescriptorRendererModifier(val includeByDefault: Boolean) {
     ACTUAL(true),
     CONST(true),
     LATEINIT(true),
+    FUN(true)
     ;
 
     companion object {
diff --git a/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.kt b/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.kt
index 1412e6590c1..8c19a076b4f 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.kt
+++ b/core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.kt
@@ -979,6 +979,7 @@ internal class DescriptorRendererImpl(
             renderModifier(builder, DescriptorRendererModifier.INNER in modifiers && klass.isInner, "inner")
             renderModifier(builder, DescriptorRendererModifier.DATA in modifiers && klass.isData, "data")
             renderModifier(builder, DescriptorRendererModifier.INLINE in modifiers && klass.isInline, "inline")
+            renderModifier(builder, DescriptorRendererModifier.FUN in modifiers && klass.isFun, "fun")
             renderClassKindPrefix(klass, builder)
         }