diff --git a/wally/texttable.py b/wally/texttable.py
index 1917663..504b04d 100644
--- a/wally/texttable.py
+++ b/wally/texttable.py
@@ -306,6 +306,7 @@
         cells = []
         for i, x in enumerate(array):
             cells.append(self._str(i, x))
+
         self._rows.append(cells)
 
     def add_rows(self, rows, header=True):
@@ -366,6 +367,9 @@
             i - index of the cell datatype in self._dtype
             x - cell data to format
         """
+        if isinstance(x, str):
+            return x
+
         try:
             f = float(x)
         except: