diff --git a/websocket-sharp/Ext.cs b/websocket-sharp/Ext.cs
index 100c08e3..270a2a84 100644
--- a/websocket-sharp/Ext.cs
+++ b/websocket-sharp/Ext.cs
@@ -516,19 +516,28 @@ namespace WebSocketSharp
     internal static bool IsText (this string value)
     {
       var len = value.Length;
+
       for (var i = 0; i < len; i++) {
         var c = value[i];
-        if (c < 0x20 && !"\r\n\t".Contains (c))
-          return false;
+        if (c < 0x20) {
+          if (!"\r\n\t".Contains (c))
+            return false;
 
-        if (c == 0x7f)
-          return false;
+          if (c == '\n') {
+            i++;
+            if (i == len)
+              break;
 
-        if (c == '\n' && ++i < len) {
-          c = value[i];
-          if (!" \t".Contains (c))
-            return false;
+            c = value[i];
+            if (!" \t".Contains (c))
+              return false;
+          }
+
+          continue;
         }
+
+        if (c == 0x7f)
+          return false;
       }
 
       return true;