diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirCastDiagnosticsHelpers.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirCastDiagnosticsHelpers.kt
index 84d334d5dc9..6ae1614e146 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirCastDiagnosticsHelpers.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/FirCastDiagnosticsHelpers.kt
@@ -128,7 +128,7 @@ fun isCastErased(supertype: ConeKotlinType, subtype: ConeKotlinType, context: Ch
     }
 
     // cast between T and T? is always OK
-    if (supertype.isMarkedNullable || subtype.isMarkedNullable) {
+    if ((supertype !is ConeErrorType && supertype.isMarkedNullable) || (subtype !is ConeErrorType && subtype.isMarkedNullable)) {
         return isCastErased(
             supertype.withNullability(ConeNullability.NOT_NULL, typeContext),
             subtype.withNullability(ConeNullability.NOT_NULL, typeContext),
diff --git a/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.fir.kt b/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.fir.kt
index 65f47e1f487..9daf96c0f54 100644
--- a/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.fir.kt
+++ b/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.fir.kt
@@ -3,4 +3,9 @@ class P
 fun foo(p: P): Any {
     val v = p as <!UNRESOLVED_REFERENCE!>G<!>
     return v
-}
\ No newline at end of file
+}
+
+fun bar(p: P): Any {
+    val v = p as <!UNRESOLVED_REFERENCE!>G<!>?
+    return v
+}
diff --git a/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.kt b/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.kt
index 84bd38b1368..6e01a0bf309 100644
--- a/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.kt
+++ b/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.kt
@@ -3,4 +3,9 @@ class P
 fun foo(p: P): Any {
     val v = p as <!UNRESOLVED_REFERENCE!>G<!>
     return <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>v<!>
-}
\ No newline at end of file
+}
+
+fun bar(p: P): Any {
+    val v = p as <!UNRESOLVED_REFERENCE!>G<!>?
+    return <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>v<!>
+}
diff --git a/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.txt b/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.txt
index a6f23f42a68..0d5fa8fb132 100644
--- a/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.txt
+++ b/compiler/testData/diagnostics/tests/cast/bare/ToErrorType.txt
@@ -1,5 +1,6 @@
 package
 
+public fun bar(/*0*/ p: P): kotlin.Any
 public fun foo(/*0*/ p: P): kotlin.Any
 
 public final class P {