diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java
index a59f36fbd4e..697df31c3ca 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/StackValue.java
@@ -281,33 +281,24 @@ public abstract class StackValue {
     }
 
     private static void box(Type type, Type toType, InstructionAdapter v) {
-        if (type == Type.BYTE_TYPE || toType.getInternalName().equals(NULLABLE_BYTE_TYPE_NAME) && type == Type.INT_TYPE) {
-            v.cast(type, Type.BYTE_TYPE);
-            v.invokestatic(NULLABLE_BYTE_TYPE_NAME, "valueOf", "(B)L" + NULLABLE_BYTE_TYPE_NAME + ";", false);
-        }
-        else if (type == Type.SHORT_TYPE || toType.getInternalName().equals(NULLABLE_SHORT_TYPE_NAME) && type == Type.INT_TYPE) {
-            v.cast(type, Type.SHORT_TYPE);
-            v.invokestatic(NULLABLE_SHORT_TYPE_NAME, "valueOf", "(S)L" + NULLABLE_SHORT_TYPE_NAME + ";", false);
-        }
-        else if (type == Type.LONG_TYPE || toType.getInternalName().equals(NULLABLE_LONG_TYPE_NAME) && type == Type.INT_TYPE) {
-            v.cast(type, Type.LONG_TYPE);
-            v.invokestatic(NULLABLE_LONG_TYPE_NAME, "valueOf", "(J)L" + NULLABLE_LONG_TYPE_NAME + ";", false);
-        }
-        else if (type == Type.INT_TYPE) {
-            v.invokestatic("java/lang/Integer", "valueOf", "(I)Ljava/lang/Integer;", false);
-        }
-        else if (type == Type.BOOLEAN_TYPE) {
-            v.invokestatic("java/lang/Boolean", "valueOf", "(Z)Ljava/lang/Boolean;", false);
-        }
-        else if (type == Type.CHAR_TYPE) {
-            v.invokestatic("java/lang/Character", "valueOf", "(C)Ljava/lang/Character;", false);
-        }
-        else if (type == Type.FLOAT_TYPE) {
-            v.invokestatic("java/lang/Float", "valueOf", "(F)Ljava/lang/Float;", false);
-        }
-        else if (type == Type.DOUBLE_TYPE) {
-            v.invokestatic("java/lang/Double", "valueOf", "(D)Ljava/lang/Double;", false);
+        if (type == Type.INT_TYPE) {
+            if (toType.getInternalName().equals(NULLABLE_BYTE_TYPE_NAME)) {
+                type = Type.BYTE_TYPE;
+            }
+            else if (toType.getInternalName().equals(NULLABLE_SHORT_TYPE_NAME)) {
+                type = Type.SHORT_TYPE;
+            }
+            else if (toType.getInternalName().equals(NULLABLE_LONG_TYPE_NAME)) {
+                type = Type.LONG_TYPE;
+            }
+            v.cast(Type.INT_TYPE, type);
         }
+
+        Type boxedType = AsmUtil.boxType(type);
+        if (boxedType == type) return;
+
+        v.invokestatic(boxedType.getInternalName(), "valueOf", Type.getMethodDescriptor(boxedType, type), false);
+        coerce(boxedType, toType,  v);
     }
 
     private static void unbox(Type type, InstructionAdapter v) {
diff --git a/compiler/testData/codegen/java8/box/jvm8/kt16581.kt b/compiler/testData/codegen/java8/box/jvm8/kt16581.kt
new file mode 100644
index 00000000000..15329e1f4d0
--- /dev/null
+++ b/compiler/testData/codegen/java8/box/jvm8/kt16581.kt
@@ -0,0 +1,9 @@
+// JVM_TARGET: 1.8
+fun failAtRuntime(numberArg: Number = 0.0): Number {
+    return numberArg
+}
+
+fun box(): String {
+    failAtRuntime()
+    return "OK"
+}
\ No newline at end of file
diff --git a/compiler/testData/codegen/java8/box/jvm8/kt16581_2.kt b/compiler/testData/codegen/java8/box/jvm8/kt16581_2.kt
new file mode 100644
index 00000000000..79807862f4f
--- /dev/null
+++ b/compiler/testData/codegen/java8/box/jvm8/kt16581_2.kt
@@ -0,0 +1,17 @@
+// JVM_TARGET: 1.8
+
+fun test(o: Number) {}
+
+fun test2(o: Number) {
+    val p: Int = 1
+    val o = if (z < 1) p else o
+    test(o)
+}
+
+var z = 1
+
+fun box(): String {
+    val x: Number = 1
+    test2(x)
+    return "OK"
+}
\ No newline at end of file
diff --git a/compiler/testData/codegen/java8/box/jvm8/kt16588.kt b/compiler/testData/codegen/java8/box/jvm8/kt16588.kt
new file mode 100644
index 00000000000..7bbd29ab2cc
--- /dev/null
+++ b/compiler/testData/codegen/java8/box/jvm8/kt16588.kt
@@ -0,0 +1,12 @@
+// JVM_TARGET: 1.8
+
+fun number(doLong: Boolean): Number = when {
+    doLong -> 1.toLong()
+    else -> 0
+}
+
+fun box(): String {
+    number(true)
+    return "OK"
+}
+
diff --git a/compiler/tests-java8/tests/org/jetbrains/kotlin/codegen/BlackBoxWithJava8CodegenTestGenerated.java b/compiler/tests-java8/tests/org/jetbrains/kotlin/codegen/BlackBoxWithJava8CodegenTestGenerated.java
index ddc46367605..4c500f433e6 100644
--- a/compiler/tests-java8/tests/org/jetbrains/kotlin/codegen/BlackBoxWithJava8CodegenTestGenerated.java
+++ b/compiler/tests-java8/tests/org/jetbrains/kotlin/codegen/BlackBoxWithJava8CodegenTestGenerated.java
@@ -269,6 +269,24 @@ public class BlackBoxWithJava8CodegenTestGenerated extends AbstractBlackBoxCodeg
             doTest(fileName);
         }
 
+        @TestMetadata("kt16581.kt")
+        public void testKt16581() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/java8/box/jvm8/kt16581.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("kt16581_2.kt")
+        public void testKt16581_2() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/java8/box/jvm8/kt16581_2.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("kt16588.kt")
+        public void testKt16588() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/java8/box/jvm8/kt16588.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("oneImplementation.kt")
         public void testOneImplementation() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/java8/box/jvm8/oneImplementation.kt");