diff --git a/std/format.d b/std/format.d
index 10adbf24b42..cd6b82ceac8 100644
--- a/std/format.d
+++ b/std/format.d
@@ -438,7 +438,7 @@ My friends are "John", "Nancy".
 My friends are John, Nancy.
 )
  */
-uint formattedWrite(alias fmt, Writer, A...)(Writer w, A args)
+uint formattedWrite(alias fmt, Writer, A...)(auto ref Writer w, A args)
 if (isSomeString!(typeof(fmt)))
 {
     alias e = checkFormatException!(fmt, A);
@@ -463,7 +463,7 @@ if (isSomeString!(typeof(fmt)))
 }
 
 /// ditto
-uint formattedWrite(Writer, Char, A...)(Writer w, in Char[] fmt, A args)
+uint formattedWrite(Writer, Char, A...)(auto ref Writer w, in Char[] fmt, A args)
 {
     import std.conv : text;
 
@@ -1163,7 +1163,7 @@ if (is(Unqual!Char == Char))
         trailing = fmt;
     }
 
-    bool writeUpToNextSpec(OutputRange)(OutputRange writer)
+    bool writeUpToNextSpec(OutputRange)(ref OutputRange writer)
     {
         if (trailing.empty)
             return false;
@@ -1724,7 +1724,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(BooleanTypeOf!T) && !is(T == enum) && !hasToString!(T, Char))
 {
     BooleanTypeOf!T val = obj;
@@ -1806,7 +1806,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(Unqual!T == typeof(null)) && !is(T == enum) && !hasToString!(T, Char))
 {
     enforceFmt(f.spec == 's',
@@ -1844,7 +1844,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(IntegralTypeOf!T) && !is(T == enum) && !hasToString!(T, Char))
 {
     alias U = IntegralTypeOf!T;
@@ -1900,7 +1900,7 @@ if (is(IntegralTypeOf!T) && !is(T == enum) && !hasToString!(T, Char))
     assert(w.data == "1337");
 }
 
-private void formatIntegral(Writer, T, Char)(Writer w, const(T) val, const ref FormatSpec!Char fs,
+private void formatIntegral(Writer, T, Char)(ref Writer w, const(T) val, const ref FormatSpec!Char fs,
     uint base, ulong mask)
 {
     T arg = val;
@@ -1918,7 +1918,8 @@ private void formatIntegral(Writer, T, Char)(Writer w, const(T) val, const ref F
         formatUnsigned(w, (cast(ulong) arg) & mask, fs, base, negative);
 }
 
-private void formatUnsigned(Writer, T, Char)(Writer w, T arg, const ref FormatSpec!Char fs, uint base, bool negative)
+private void formatUnsigned(Writer, T, Char)
+(ref Writer w, T arg, const ref FormatSpec!Char fs, uint base, bool negative)
 {
     /* Write string:
      *    leftpad prefix1 prefix2 zerofill digits rightpad
@@ -2120,7 +2121,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(FloatingPointTypeOf!T) && !is(T == enum) && !hasToString!(T, Char))
 {
     import std.algorithm.comparison : min;
@@ -2344,7 +2345,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(Unqual!T : creal) && !is(T == enum) && !hasToString!(T, Char))
 {
     immutable creal val = obj;
@@ -2400,7 +2401,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(Unqual!T : ireal) && !is(T == enum) && !hasToString!(T, Char))
 {
     immutable ireal val = obj;
@@ -2447,7 +2448,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(CharTypeOf!T) && !is(T == enum) && !hasToString!(T, Char))
 {
     CharTypeOf!T val = obj;
@@ -2520,7 +2521,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(StringTypeOf!T) && !is(StaticArrayTypeOf!T) && !is(T == enum) && !hasToString!(T, Char))
 {
     Unqual!(StringTypeOf!T) val = obj;  // for `alias this`, see bug5371
@@ -2598,7 +2599,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, auto ref T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, auto ref T obj, const ref FormatSpec!Char f)
 if (is(StaticArrayTypeOf!T) && !is(T == enum) && !hasToString!(T, Char))
 {
     formatValue(w, obj[], f);
@@ -2641,7 +2642,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(DynamicArrayTypeOf!T) && !is(StringTypeOf!T) && !is(T == enum) && !hasToString!(T, Char))
 {
     static if (is(const(ArrayTypeOf!T) == const(void[])))
@@ -3024,7 +3025,7 @@ if (isInputRange!T)
 }
 
 // character formatting with ecaping
-private void formatChar(Writer)(Writer w, in dchar c, in char quote)
+private void formatChar(Writer)(ref Writer w, in dchar c, in char quote)
 {
     import std.uni : isGraphical;
 
@@ -3062,7 +3063,7 @@ private void formatChar(Writer)(Writer w, in dchar c, in char quote)
 
 // undocumented because of deprecation
 // string elements are formatted like UTF-8 string literals.
-void formatElement(Writer, T, Char)(Writer w, T val, const ref FormatSpec!Char f)
+void formatElement(Writer, T, Char)(auto ref Writer w, T val, const ref FormatSpec!Char f)
 if (is(StringTypeOf!T) && !is(T == enum))
 {
     import std.array : appender;
@@ -3147,7 +3148,7 @@ if (is(StringTypeOf!T) && !is(T == enum))
 
 // undocumented because of deprecation
 // Character elements are formatted like UTF-8 character literals.
-void formatElement(Writer, T, Char)(Writer w, T val, const ref FormatSpec!Char f)
+void formatElement(Writer, T, Char)(auto ref Writer w, T val, const ref FormatSpec!Char f)
 if (is(CharTypeOf!T) && !is(T == enum))
 {
     if (f.spec == 's')
@@ -3173,7 +3174,7 @@ if (is(CharTypeOf!T) && !is(T == enum))
 
 // undocumented
 // Maybe T is noncopyable struct, so receive it by 'auto ref'.
-void formatElement(Writer, T, Char)(Writer w, auto ref T val, const ref FormatSpec!Char f)
+void formatElement(Writer, T, Char)(auto ref Writer w, auto ref T val, const ref FormatSpec!Char f)
 if (!is(StringTypeOf!T) && !is(CharTypeOf!T) || is(T == enum))
 {
     formatValue(w, val, f);
@@ -3188,7 +3189,7 @@ Params:
     obj = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T obj, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T obj, const ref FormatSpec!Char f)
 if (is(AssocArrayTypeOf!T) && !is(T == enum) && !hasToString!(T, Char))
 {
     AssocArrayTypeOf!T val = obj;
@@ -3433,7 +3434,7 @@ const string toString();
 
    Otherwise, are formatted just as their type name.
  */
-void formatValue(Writer, T, Char)(Writer w, T val, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T val, const ref FormatSpec!Char f)
 if (is(T == class) && !is(T == enum))
 {
     enforceValidFormatSpec!(T, Char)(f);
@@ -3582,7 +3583,7 @@ if (is(T == class) && !is(T == enum))
 }
 
 /// ditto
-void formatValue(Writer, T, Char)(Writer w, T val, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T val, const ref FormatSpec!Char f)
 if (is(T == interface) && (hasToString!(T, Char) || !is(BuiltinTypeOf!T)) && !is(T == enum))
 {
     enforceValidFormatSpec!(T, Char)(f);
@@ -3662,7 +3663,7 @@ if (is(T == interface) && (hasToString!(T, Char) || !is(BuiltinTypeOf!T)) && !is
 
 /// ditto
 // Maybe T is noncopyable struct, so receive it by 'auto ref'.
-void formatValue(Writer, T, Char)(Writer w, auto ref T val, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, auto ref T val, const ref FormatSpec!Char f)
 if ((is(T == struct) || is(T == union)) && (hasToString!(T, Char) || !is(BuiltinTypeOf!T)) && !is(T == enum))
 {
     enforceValidFormatSpec!(T, Char)(f);
@@ -3797,7 +3798,7 @@ Params:
     val = The value to write.
     f = The $(D FormatSpec) defining how to write the value.
  */
-void formatValue(Writer, T, Char)(Writer w, T val, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T val, const ref FormatSpec!Char f)
 if (is(T == enum))
 {
     if (f.spec == 's')
@@ -3866,7 +3867,7 @@ if (is(T == enum))
 /**
    Pointers are formatted as hex integers.
  */
-void formatValue(Writer, T, Char)(Writer w, T val, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, T val, const ref FormatSpec!Char f)
 if (isPointer!T && !is(T == enum) && !hasToString!(T, Char))
 {
     static if (isInputRange!T)
@@ -3971,7 +3972,7 @@ if (isPointer!T && !is(T == enum) && !hasToString!(T, Char))
 /**
    Delegates are formatted by 'ReturnType delegate(Parameters) FunctionAttributes'
  */
-void formatValue(Writer, T, Char)(Writer w, scope T, const ref FormatSpec!Char f)
+void formatValue(Writer, T, Char)(auto ref Writer w, scope T, const ref FormatSpec!Char f)
 if (isDelegate!T)
 {
     formatValue(w, T.stringof, f);