diff --git a/generators/builtins/unsignedTypes.kt b/generators/builtins/unsignedTypes.kt
index 0653c62adba..8fb672183cd 100644
--- a/generators/builtins/unsignedTypes.kt
+++ b/generators/builtins/unsignedTypes.kt
@@ -199,7 +199,11 @@ class UnsignedTypeGenerator(val type: UnsignedType, out: PrintWriter) : BuiltIns
         for (otherType in UnsignedType.values()) {
             val name = otherType.capitalized
             out.print("    public fun to$name(): $name = ")
-            out.println(if (type == otherType) "this" else "data.to${otherType.capitalized}()")
+            out.println(when {
+                otherType > type -> "data.to${otherType.capitalized}() and ${type.mask}u"
+                otherType == type -> "this"
+                else -> "data.to${otherType.capitalized}()"
+            })
         }
         out.println()
     }
@@ -212,7 +216,6 @@ class UnsignedTypeGenerator(val type: UnsignedType, out: PrintWriter) : BuiltIns
             out.println("@ExperimentalUnsignedTypes")
             out.print("public fun $otherSigned.to$className(): $className = ")
             out.println(when {
-                otherType < type -> "$className(this.to$thisSigned() and ${otherType.mask})"
                 otherType == type -> "$className(this)"
                 else -> "$className(this.to$thisSigned())"
             })
diff --git a/libraries/stdlib/unsigned/src/kotlin/UByte.kt b/libraries/stdlib/unsigned/src/kotlin/UByte.kt
index 4ed06b39565..a936e425aff 100644
--- a/libraries/stdlib/unsigned/src/kotlin/UByte.kt
+++ b/libraries/stdlib/unsigned/src/kotlin/UByte.kt
@@ -132,9 +132,9 @@ public inline class UByte internal constructor(private val data: Byte) : Compara
     public fun toLong(): Long = data.toLong() and 0xFF
 
     public fun toUByte(): UByte = this
-    public fun toUShort(): UShort = data.toUShort()
-    public fun toUInt(): UInt = data.toUInt()
-    public fun toULong(): ULong = data.toULong()
+    public fun toUShort(): UShort = data.toUShort() and 0xFFu
+    public fun toUInt(): UInt = data.toUInt() and 0xFFu
+    public fun toULong(): ULong = data.toULong() and 0xFFu
 
     public override fun toString(): String = toInt().toString()
 
diff --git a/libraries/stdlib/unsigned/src/kotlin/UInt.kt b/libraries/stdlib/unsigned/src/kotlin/UInt.kt
index bf6560144cc..5664db87ef2 100644
--- a/libraries/stdlib/unsigned/src/kotlin/UInt.kt
+++ b/libraries/stdlib/unsigned/src/kotlin/UInt.kt
@@ -138,7 +138,7 @@ public inline class UInt internal constructor(private val data: Int) : Comparabl
     public fun toUByte(): UByte = data.toUByte()
     public fun toUShort(): UShort = data.toUShort()
     public fun toUInt(): UInt = this
-    public fun toULong(): ULong = data.toULong()
+    public fun toULong(): ULong = data.toULong() and 0xFFFF_FFFFu
 
     public override fun toString(): String = toLong().toString()
 
@@ -146,10 +146,10 @@ public inline class UInt internal constructor(private val data: Int) : Comparabl
 
 @SinceKotlin("1.3")
 @ExperimentalUnsignedTypes
-public fun Byte.toUInt(): UInt = UInt(this.toInt() and 0xFF)
+public fun Byte.toUInt(): UInt = UInt(this.toInt())
 @SinceKotlin("1.3")
 @ExperimentalUnsignedTypes
-public fun Short.toUInt(): UInt = UInt(this.toInt() and 0xFFFF)
+public fun Short.toUInt(): UInt = UInt(this.toInt())
 @SinceKotlin("1.3")
 @ExperimentalUnsignedTypes
 public fun Int.toUInt(): UInt = UInt(this)
diff --git a/libraries/stdlib/unsigned/src/kotlin/ULong.kt b/libraries/stdlib/unsigned/src/kotlin/ULong.kt
index 3cf24982049..f55d589e90b 100644
--- a/libraries/stdlib/unsigned/src/kotlin/ULong.kt
+++ b/libraries/stdlib/unsigned/src/kotlin/ULong.kt
@@ -146,13 +146,13 @@ public inline class ULong internal constructor(private val data: Long) : Compara
 
 @SinceKotlin("1.3")
 @ExperimentalUnsignedTypes
-public fun Byte.toULong(): ULong = ULong(this.toLong() and 0xFF)
+public fun Byte.toULong(): ULong = ULong(this.toLong())
 @SinceKotlin("1.3")
 @ExperimentalUnsignedTypes
-public fun Short.toULong(): ULong = ULong(this.toLong() and 0xFFFF)
+public fun Short.toULong(): ULong = ULong(this.toLong())
 @SinceKotlin("1.3")
 @ExperimentalUnsignedTypes
-public fun Int.toULong(): ULong = ULong(this.toLong() and 0xFFFF_FFFF)
+public fun Int.toULong(): ULong = ULong(this.toLong())
 @SinceKotlin("1.3")
 @ExperimentalUnsignedTypes
 public fun Long.toULong(): ULong = ULong(this)
diff --git a/libraries/stdlib/unsigned/src/kotlin/UShort.kt b/libraries/stdlib/unsigned/src/kotlin/UShort.kt
index 57b64e0a202..e576a31d8f8 100644
--- a/libraries/stdlib/unsigned/src/kotlin/UShort.kt
+++ b/libraries/stdlib/unsigned/src/kotlin/UShort.kt
@@ -133,8 +133,8 @@ public inline class UShort internal constructor(private val data: Short) : Compa
 
     public fun toUByte(): UByte = data.toUByte()
     public fun toUShort(): UShort = this
-    public fun toUInt(): UInt = data.toUInt()
-    public fun toULong(): ULong = data.toULong()
+    public fun toUInt(): UInt = data.toUInt() and 0xFFFFu
+    public fun toULong(): ULong = data.toULong() and 0xFFFFu
 
     public override fun toString(): String = toInt().toString()
 
@@ -142,7 +142,7 @@ public inline class UShort internal constructor(private val data: Short) : Compa
 
 @SinceKotlin("1.3")
 @ExperimentalUnsignedTypes
-public fun Byte.toUShort(): UShort = UShort(this.toShort() and 0xFF)
+public fun Byte.toUShort(): UShort = UShort(this.toShort())
 @SinceKotlin("1.3")
 @ExperimentalUnsignedTypes
 public fun Short.toUShort(): UShort = UShort(this)