diff --git a/changelog.md b/changelog.md
index cb87e960e9..ea2c8a927d 100644
--- a/changelog.md
+++ b/changelog.md
@@ -45,6 +45,7 @@
 - A bug allowed `macro foo(): int = 123` to compile even though a
   macros has to return a `NimNode`. This has been fixed.
 
+- With the exception of `uint` and `uint64`, conversion to unsigned types are now range checked during runtime.
 
 #### Breaking changes in the standard library
 
diff --git a/compiler/ccgexprs.nim b/compiler/ccgexprs.nim
index 2991ca2e26..2312ce9fd7 100644
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -1959,9 +1959,7 @@ proc genCast(p: BProc, e: PNode, d: var TLoc) =
 proc genRangeChck(p: BProc, n: PNode, d: var TLoc, magic: string) =
   var a: TLoc
   var dest = skipTypes(n.typ, abstractVar)
-  # range checks for unsigned turned out to be buggy and annoying:
-  if optRangeCheck notin p.options or dest.skipTypes({tyRange}).kind in
-                                             {tyUInt..tyUInt64}:
+  if optRangeCheck notin p.options:
     initLocExpr(p, n.sons[0], a)
     putIntoDest(p, d, n, "(($1) ($2))" %
         [getTypeDesc(p.module, dest), rdCharLoc(a)], a.storage)
diff --git a/compiler/lexer.nim b/compiler/lexer.nim
index 0dd6245b02..52559dad51 100644
--- a/compiler/lexer.nim
+++ b/compiler/lexer.nim
@@ -538,9 +538,9 @@ proc getNumber(L: var TLexer, result: var TToken) =
       of tkInt16Lit: result.iNumber = BiggestInt(int16(toU16(int(xi))))
       of tkInt32Lit: result.iNumber = BiggestInt(int32(toU32(int64(xi))))
       of tkUIntLit, tkUInt64Lit: result.iNumber = xi
-      of tkUInt8Lit: result.iNumber = BiggestInt(uint8(toU8(int(xi))))
-      of tkUInt16Lit: result.iNumber = BiggestInt(uint16(toU16(int(xi))))
-      of tkUInt32Lit: result.iNumber = BiggestInt(uint32(toU32(int64(xi))))
+      of tkUInt8Lit: result.iNumber = BiggestInt(cast[uint8](toU8(int(xi))))
+      of tkUInt16Lit: result.iNumber = BiggestInt(cast[uint16](toU16(int(xi))))
+      of tkUInt32Lit: result.iNumber = BiggestInt(cast[uint32](toU32(int64(xi))))
       of tkFloat32Lit:
         result.fNumber = (cast[PFloat32](addr(xi)))[]
         # note: this code is endian neutral!
diff --git a/lib/pure/bitops.nim b/lib/pure/bitops.nim
index b32b5dc671..51e4a6c6a0 100644
--- a/lib/pure/bitops.nim
+++ b/lib/pure/bitops.nim
@@ -33,6 +33,12 @@ const useICC_builtins = defined(icc) and useBuiltins
 const useVCC_builtins = defined(vcc) and useBuiltins
 const arch64 = sizeof(int) == 8
 
+template toUnsigned(x: int8): uint8 = cast[uint8](x)
+template toUnsigned(x: int16): uint16 = cast[uint16](x)
+template toUnsigned(x: int32): uint32 = cast[uint32](x)
+template toUnsigned(x: int64): uint64 = cast[uint64](x)
+template toUnsigned(x: int): uint = cast[uint](x)
+
 template forwardImpl(impl, arg) {.dirty.} =
   when sizeof(x) <= 4:
     when x is SomeSignedInt:
@@ -242,6 +248,8 @@ proc countSetBits*(x: SomeInteger): int {.inline, nosideeffect.} =
   ## Counts the set bits in integer. (also called `Hamming weight`:idx:.)
   # TODO: figure out if ICC support _popcnt32/_popcnt64 on platform without POPCNT.
   # like GCC and MSVC
+  when x is SomeSignedInt:
+    let x = x.toUnsigned
   when nimvm:
     result = forwardImpl(countSetBits_nim, x)
   else:
@@ -272,6 +280,8 @@ proc parityBits*(x: SomeInteger): int {.inline, nosideeffect.} =
   ## is odd parity is 1, otherwise 0.
   # Can be used a base if creating ASM version.
   # https://stackoverflow.com/questions/21617970/how-to-check-if-value-has-even-parity-of-bits-or-odd
+  when x is SomeSignedInt:
+    let x = x.toUnsigned
   when nimvm:
     result = forwardImpl(parity_impl, x)
   else:
@@ -287,6 +297,8 @@ proc firstSetBit*(x: SomeInteger): int {.inline, nosideeffect.} =
   ## If `x` is zero, when ``noUndefinedBitOpts`` is set, result is 0,
   ## otherwise result is undefined.
   # GCC builtin 'builtin_ffs' already handle zero input.
+  when x is SomeSignedInt:
+    let x = x.toUnsigned
   when nimvm:
     when noUndefined:
       if x == 0:
@@ -321,6 +333,8 @@ proc fastLog2*(x: SomeInteger): int {.inline, nosideeffect.} =
   ## Quickly find the log base 2 of an integer.
   ## If `x` is zero, when ``noUndefinedBitOpts`` is set, result is -1,
   ## otherwise result is undefined.
+  when x is SomeSignedInt:
+    let x = x.toUnsigned
   when noUndefined:
     if x == 0:
       return -1
@@ -352,6 +366,8 @@ proc countLeadingZeroBits*(x: SomeInteger): int {.inline, nosideeffect.} =
   ## Returns the number of leading zero bits in integer.
   ## If `x` is zero, when ``noUndefinedBitOpts`` is set, result is 0,
   ## otherwise result is undefined.
+  when x is SomeSignedInt:
+    let x = x.toUnsigned
   when noUndefined:
     if x == 0:
       return 0
@@ -369,6 +385,8 @@ proc countTrailingZeroBits*(x: SomeInteger): int {.inline, nosideeffect.} =
   ## Returns the number of trailing zeros in integer.
   ## If `x` is zero, when ``noUndefinedBitOpts`` is set, result is 0,
   ## otherwise result is undefined.
+  when x is SomeSignedInt:
+    let x = x.toUnsigned
   when noUndefined:
     if x == 0:
       return 0
diff --git a/tests/misc/tsizeof3.nim b/tests/misc/tsizeof3.nim
index 50ad883713..e41e0a2688 100644
--- a/tests/misc/tsizeof3.nim
+++ b/tests/misc/tsizeof3.nim
@@ -13,7 +13,7 @@ proc toByteArrayBE*[T: SomeInteger](num: T): ByteArrayBE[sizeof(T)]=
   ## Notice the result type
   const N = T.sizeof
   for i in 0 ..< N:
-    result[i] = byte(num shr ((N-1-i) * 8))
+    result[i] = byte((num shr ((N-1-i) * 8)) and high(int8))
 
 let a = 12345.toByteArrayBE
 echo a[^2 .. ^1] # to make it work on both 32-bit and 64-bit