fixes #11723

2 files changed, 20 insertions, 2 deletions

diff --git a/lib/pure/strformat.nim b/lib/pure/strformat.nim
index d3026165a..ba75ce95f 100644
--- a/lib/pure/strformat.nim
+++ b/lib/pure/strformat.nim
@@ -415,7 +415,7 @@ proc parseStandardFormatSpecifier*(s: string; start = 0;
     raise newException(ValueError,
       "invalid format string, cannot parse: " & s[i..^1])
 
-proc formatValue*(result: var string; value: SomeInteger; specifier: string) =
+proc formatValue*[T: SomeInteger](result: var string; value: T; specifier: string) =
   ## Standard format implementation for ``SomeInteger``. It makes little
   ## sense to call this directly, but it is required to exist
   ## by the ``&`` macro.
@@ -509,7 +509,7 @@ proc formatValue*(result: var string; value: string; specifier: string) =
       setLen(value, runeOffset(value, spec.precision))
   result.add alignString(value, spec.minimumWidth, spec.align, spec.fill)
 
-proc formatValue[T](result: var string; value: T; specifier: string) =
+proc formatValue[T: not SomeInteger](result: var string; value: T; specifier: string) =
   mixin `$`
   formatValue(result, $value, specifier)
 
diff --git a/tests/stdlib/tstrformat.nim b/tests/stdlib/tstrformat.nim
index 188ce8106..732283674 100644
--- a/tests/stdlib/tstrformat.nim
+++ b/tests/stdlib/tstrformat.nim
@@ -115,3 +115,21 @@ proc print_object(animalAddr: AnimalRef) =
   echo fmt"Received {animalAddr[]}"
 
 print_object(AnimalRef(name: "Foo", species: "Bar"))
+
+# bug #11723
+
+let pos: Positive = 64
+doAssert fmt"{pos:3}" == " 64"
+doAssert fmt"{pos:3b}" == "1000000"
+doAssert fmt"{pos:3d}" == " 64"
+doAssert fmt"{pos:3o}" == "100"
+doAssert fmt"{pos:3x}" == " 40"
+doAssert fmt"{pos:3X}" == " 40"
+
+let nat: Natural = 64
+doAssert fmt"{nat:3}" == " 64"
+doAssert fmt"{nat:3b}" == "1000000"
+doAssert fmt"{nat:3d}" == " 64"
+doAssert fmt"{nat:3o}" == "100"
+doAssert fmt"{nat:3x}" == " 40"
+doAssert fmt"{nat:3X}" == " 40"