diff --git a/cs/ccxt/base/Exchange.Number.cs b/cs/ccxt/base/Exchange.Number.cs
index db83dd619785..efa352492798 100644
--- a/cs/ccxt/base/Exchange.Number.cs
+++ b/cs/ccxt/base/Exchange.Number.cs
@@ -300,6 +300,8 @@ public static string NumberToString(object number)
     {
         if (number == null)
             return null;
+        if (number.GetType() == typeof(string))
+            return number as string;
         if (number.GetType() == typeof(Int32) || number.GetType() == typeof(Int64))
             return number.ToString();
 
diff --git a/python/ccxt/base/decimal_to_precision.py b/python/ccxt/base/decimal_to_precision.py
index 4be38f010765..6dccb5faec05 100644
--- a/python/ccxt/base/decimal_to_precision.py
+++ b/python/ccxt/base/decimal_to_precision.py
@@ -169,6 +169,8 @@ def number_to_string(x):
     # avoids scientific notation for too large and too small numbers
     if x is None:
         return None
+    if isinstance(x, str):
+        return x
     d = decimal.Decimal(str(x))
     formatted = '{:f}'.format(d)
     return formatted.rstrip('0').rstrip('.') if '.' in formatted else formatted
diff --git a/ts/src/base/functions/number.ts b/ts/src/base/functions/number.ts
index 15a3167b904d..6da47ba44a26 100644
--- a/ts/src/base/functions/number.ts
+++ b/ts/src/base/functions/number.ts
@@ -39,6 +39,7 @@ const precisionConstants = {
 
 function numberToString (x) { // avoids scientific notation for too large and too small numbers
     if (x === undefined) return undefined;
+    if (typeof x === 'string') return x;
     if (typeof x !== 'number') return x.toString ();
     const s = x.toString ();
     if (Math.abs (x) < 1.0) {