diff --git a/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java b/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java
index ac1904811a0..f39e7839318 100644
--- a/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java
+++ b/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java
@@ -13927,6 +13927,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
             public void testUnitInContravariantPosition() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.kt");
             }
+
+            @Test
+            @TestMetadata("unitInCovariantPosition.kt")
+            public void testUnitInCovariantPosition() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.kt");
+            }
         }
 
         @Nested
diff --git a/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java b/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java
index d90bfbf5363..ba3f49f2c4e 100644
--- a/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java
+++ b/analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java
@@ -13927,6 +13927,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
             public void testUnitInContravariantPosition() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.kt");
             }
+
+            @Test
+            @TestMetadata("unitInCovariantPosition.kt")
+            public void testUnitInCovariantPosition() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.kt");
+            }
         }
 
         @Nested
diff --git a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeOldFrontendDiagnosticsTestGenerated.java b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeOldFrontendDiagnosticsTestGenerated.java
index f1748246244..708c976cb8e 100644
--- a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeOldFrontendDiagnosticsTestGenerated.java
+++ b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeOldFrontendDiagnosticsTestGenerated.java
@@ -13921,6 +13921,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
             public void testUnitInContravariantPosition() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.kt");
             }
+
+            @Test
+            @TestMetadata("unitInCovariantPosition.kt")
+            public void testUnitInCovariantPosition() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.kt");
+            }
         }
 
         @Nested
diff --git a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiOldFrontendDiagnosticsTestGenerated.java b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiOldFrontendDiagnosticsTestGenerated.java
index 3ee12df7cef..34794394052 100644
--- a/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiOldFrontendDiagnosticsTestGenerated.java
+++ b/compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiOldFrontendDiagnosticsTestGenerated.java
@@ -13927,6 +13927,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
             public void testUnitInContravariantPosition() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.kt");
             }
+
+            @Test
+            @TestMetadata("unitInCovariantPosition.kt")
+            public void testUnitInCovariantPosition() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.kt");
+            }
         }
 
         @Nested
diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/SamResolution.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/SamResolution.kt
index 1c055a6c0d5..cece23d5e52 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/SamResolution.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/SamResolution.kt
@@ -81,10 +81,11 @@ class FirSamResolver(
             }
 
             is ConeStubType, is ConeTypeParameterType, is ConeTypeVariableType,
-            is ConeCapturedType, is ConeDefinitelyNotNullType, is ConeIntersectionType,
-            is ConeIntegerLiteralType,
+            is ConeDefinitelyNotNullType, is ConeIntersectionType, is ConeIntegerLiteralType,
             -> null
 
+            is ConeCapturedType -> type.lowerType?.let { getFunctionTypeForPossibleSamType(it) }
+
             is ConeLookupTagBasedType -> unreachableBranch(type)
         }
     }
diff --git a/compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.fir.kt b/compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.fir.kt
deleted file mode 100644
index 985d190f726..00000000000
--- a/compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.fir.kt
+++ /dev/null
@@ -1,17 +0,0 @@
-// ISSUE: KT-63379
-
-class TestDummyClass<T> {
-    fun testFun(t: T) {}
-}
-
-fun more(t: TestDummyClass<in CustomRunnable>) {
-    t.testFun <!ARGUMENT_TYPE_MISMATCH!>{ Unit }<!>
-    t.testFun(CustomRunnable { Unit })
-    t.testFun(object : CustomRunnable {
-        override fun run() {}
-    })
-}
-
-fun interface CustomRunnable {
-    fun run()
-}
diff --git a/compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.kt b/compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.kt
index a09f01e73f8..fbd2e07d46f 100644
--- a/compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.kt
+++ b/compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.kt
@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // ISSUE: KT-63379
 
 class TestDummyClass<T> {
diff --git a/compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.fir.kt b/compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.fir.kt
new file mode 100644
index 00000000000..1a138472dab
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.fir.kt
@@ -0,0 +1,17 @@
+// ISSUE: KT-63379 (modified example, see original in unitInContravariantPosition.kt)
+
+class TestDummyClass<T> {
+    fun testFun(t: T) {}
+}
+
+fun more(t: TestDummyClass<out CustomRunnable>) {
+    t.testFun <!ARGUMENT_TYPE_MISMATCH!>{ Unit }<!>
+    t.testFun(<!ARGUMENT_TYPE_MISMATCH!>CustomRunnable { Unit }<!>)
+    t.testFun(<!ARGUMENT_TYPE_MISMATCH!>object : CustomRunnable<!> {
+        override fun run() {}
+    })
+}
+
+fun interface CustomRunnable {
+    fun run()
+}
diff --git a/compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.kt b/compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.kt
new file mode 100644
index 00000000000..cb5d1e7f963
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.kt
@@ -0,0 +1,17 @@
+// ISSUE: KT-63379 (modified example, see original in unitInContravariantPosition.kt)
+
+class TestDummyClass<T> {
+    fun testFun(t: T) {}
+}
+
+fun more(t: TestDummyClass<out CustomRunnable>) {
+    t.testFun <!TYPE_MISMATCH!>{ Unit }<!>
+    t.testFun(<!TYPE_MISMATCH!>CustomRunnable { Unit }<!>)
+    t.testFun(<!TYPE_MISMATCH!>object : CustomRunnable<!> {
+        override fun run() {}
+    })
+}
+
+fun interface CustomRunnable {
+    fun run()
+}
diff --git a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java
index e2704383dd9..d379e7480b6 100644
--- a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java
+++ b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java
@@ -13927,6 +13927,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
             public void testUnitInContravariantPosition() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/funInterface/unitInContravariantPosition.kt");
             }
+
+            @Test
+            @TestMetadata("unitInCovariantPosition.kt")
+            public void testUnitInCovariantPosition() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/funInterface/unitInCovariantPosition.kt");
+            }
         }
 
         @Nested