diff --git a/compiler/testData/codegen/box/exclExcl/genericNull.kt b/compiler/testData/codegen/box/exclExcl/genericNull.kt
index e8712197eac..0d4f831dfb7 100644
--- a/compiler/testData/codegen/box/exclExcl/genericNull.kt
+++ b/compiler/testData/codegen/box/exclExcl/genericNull.kt
@@ -1,6 +1,3 @@
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS
-
 fun <T> foo(t: T) {
     t!!
 }
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java
index 412e2562a33..835e3772f7e 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/BoxJsTestGenerated.java
@@ -1753,6 +1753,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("explicitUpcast.kt")
+            public void testExplicitUpcast() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/expression/cast/explicitUpcast.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("implicitCastToLong.kt")
             public void testImplicitCastToLong() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/expression/cast/implicitCastToLong.kt");
@@ -6887,6 +6893,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("js/js.translator/testData/box/safeCall"), Pattern.compile("^([^_](.+))\\.kt$"), TargetBackend.JS, true);
         }
 
+        @TestMetadata("redundantSafeAccess.kt")
+        public void testRedundantSafeAccess() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/safeCall/redundantSafeAccess.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("safeAccess.kt")
         public void testSafeAccess() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("js/js.translator/testData/box/safeCall/safeAccess.kt");
diff --git a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
index 03fb3e3748b..cbd281a9eb5 100644
--- a/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
+++ b/js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java
@@ -7851,13 +7851,7 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
         @TestMetadata("genericNull.kt")
         public void testGenericNull() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/exclExcl/genericNull.kt");
-            try {
-                doTest(fileName);
-            }
-            catch (Throwable ignore) {
-                return;
-            }
-            throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
+            doTest(fileName);
         }
 
         @TestMetadata("primitive.kt")
diff --git a/js/js.translator/src/org/jetbrains/kotlin/js/translate/operation/UnaryOperationTranslator.java b/js/js.translator/src/org/jetbrains/kotlin/js/translate/operation/UnaryOperationTranslator.java
index 2e20722f22a..0e7664d5e1a 100644
--- a/js/js.translator/src/org/jetbrains/kotlin/js/translate/operation/UnaryOperationTranslator.java
+++ b/js/js.translator/src/org/jetbrains/kotlin/js/translate/operation/UnaryOperationTranslator.java
@@ -29,12 +29,10 @@ import org.jetbrains.kotlin.lexer.KtTokens;
 import org.jetbrains.kotlin.psi.KtConstantExpression;
 import org.jetbrains.kotlin.psi.KtExpression;
 import org.jetbrains.kotlin.psi.KtUnaryExpression;
-import org.jetbrains.kotlin.resolve.BindingContextUtils;
 import org.jetbrains.kotlin.resolve.calls.callUtil.CallUtilKt;
 import org.jetbrains.kotlin.resolve.calls.model.ResolvedCall;
 import org.jetbrains.kotlin.resolve.constants.CompileTimeConstant;
 import org.jetbrains.kotlin.resolve.constants.evaluate.ConstantExpressionEvaluator;
-import org.jetbrains.kotlin.types.KotlinType;
 
 import static org.jetbrains.kotlin.js.translate.general.Translation.translateAsExpression;
 import static org.jetbrains.kotlin.js.translate.utils.BindingUtils.getCompileTimeValue;
@@ -55,9 +53,8 @@ public final class UnaryOperationTranslator {
         IElementType operationToken = expression.getOperationReference().getReferencedNameElementType();
         if (operationToken == KtTokens.EXCLEXCL) {
             KtExpression baseExpression = getBaseExpression(expression);
-            KotlinType type = BindingContextUtils.getTypeNotNull(context.bindingContext(), baseExpression);
             JsExpression translatedExpression = translateAsExpression(baseExpression, context);
-            return type.isMarkedNullable() ? sure(translatedExpression, context) : translatedExpression;
+            return sure(translatedExpression, context);
         }
 
         if (operationToken == KtTokens.MINUS) {
diff --git a/js/js.translator/testData/box/expression/cast/explicitUpcast.js b/js/js.translator/testData/box/expression/cast/explicitUpcast.js
new file mode 100644
index 00000000000..8217e075b0e
--- /dev/null
+++ b/js/js.translator/testData/box/expression/cast/explicitUpcast.js
@@ -0,0 +1,3 @@
+function createWrongObject() {
+    return new (JS_TESTS.foo.C);
+}
\ No newline at end of file
diff --git a/js/js.translator/testData/box/expression/cast/explicitUpcast.kt b/js/js.translator/testData/box/expression/cast/explicitUpcast.kt
new file mode 100644
index 00000000000..5a6ea35bd39
--- /dev/null
+++ b/js/js.translator/testData/box/expression/cast/explicitUpcast.kt
@@ -0,0 +1,34 @@
+package foo
+
+open class A
+
+class B : A()
+
+class C
+
+fun box(): String {
+    var b: B = createWrongObject()
+    if (b is A) return "fail1: is"
+    if (b as? A != null) return "fail1: as?"
+    try {
+        println(b as A)
+        return "fail1: as"
+    }
+    catch (e: ClassCastException) {
+        // It's expected
+    }
+
+    b = B()
+    if (b !is A) return "fail2: is"
+    if (b as? A == null) return "fail2: as?"
+    try {
+        if ((b as A) != b) return "fail2: as"
+    }
+    catch (e: ClassCastException) {
+        return "fail2a: as"
+    }
+
+    return "OK"
+}
+
+external fun createWrongObject(): B
\ No newline at end of file
diff --git a/js/js.translator/testData/box/safeCall/redundantSafeAccess.js b/js/js.translator/testData/box/safeCall/redundantSafeAccess.js
new file mode 100644
index 00000000000..bee74b59b4a
--- /dev/null
+++ b/js/js.translator/testData/box/safeCall/redundantSafeAccess.js
@@ -0,0 +1,3 @@
+function createWrongObject() {
+    return null
+}
\ No newline at end of file
diff --git a/js/js.translator/testData/box/safeCall/redundantSafeAccess.kt b/js/js.translator/testData/box/safeCall/redundantSafeAccess.kt
new file mode 100644
index 00000000000..917d28e1086
--- /dev/null
+++ b/js/js.translator/testData/box/safeCall/redundantSafeAccess.kt
@@ -0,0 +1,32 @@
+package foo
+
+class A(val x: String) {
+    fun foo() = x
+}
+
+fun box(): String {
+    var b: A = createWrongObject()
+    if (b?.x != null) return "fail1: ?."
+    if (b?.foo() != null) return "fail1a: ?."
+    try {
+        println(b!!.x)
+        return "fail1: !!"
+    }
+    catch (e: NullPointerException) {
+        // It's expected
+    }
+
+    b = A("OK")
+    if (b?.x != "OK") return "fail2: ?."
+    if (b?.foo() != "OK") return "fail2a: ?."
+    try {
+        if (b!!.x != "OK") return "fail2: !!"
+    }
+    catch (e: NullPointerException) {
+        return "fail2a: !!"
+    }
+
+    return "OK"
+}
+
+external fun createWrongObject(): A
\ No newline at end of file