diff --git a/src/pyRestTable/rest_table.py b/src/pyRestTable/rest_table.py
index 7c2055d..316996d 100644
--- a/src/pyRestTable/rest_table.py
+++ b/src/pyRestTable/rest_table.py
@@ -372,15 +372,24 @@ def find_widths(self):
         measure the maximum width of each column, 
         considering possible line breaks in each cell
         """
+        
+        def col_widths(columns):
+            result = []
+            for s in columns:
+                # if multi-line, get width of biggest line
+                widths = [len(p) for p in str(s).split("\n")]
+                result.append(max(widths))
+            return result
+        
         width = []
         if len(self.labels) > 0:
-            width = [max(map(len, str(_).split("\n"))) for _ in self.labels]
+            width = col_widths(self.labels)
         for row in self.rows:
             
-            row_width = [max(map(len, str(_ or '').split("\n"))) for _ in row]
+            row_width = col_widths(row)
             
             if len(width) == 0:
                 width = row_width
-            width = list(map( max, zip(width, row_width) ))
+            width = list(map(max, zip(width, row_width) ))
         return width
 
diff --git a/tests/test_results.py b/tests/test_results.py
index e361ff5..d573c30 100644
--- a/tests/test_results.py
+++ b/tests/test_results.py
@@ -395,8 +395,8 @@ def test_issue_31(self):
             ]
         for i in range(len(s)):
             msg = "row %d: " % (i+1)
-            msg += "\n  received: %s" + s[i]
-            msg += "\n  expected: %s" + expected[i]
+            msg += "\n  received: " + s[i]
+            msg += "\n  expected: " + expected[i]
             self.assertEqual(s[i], expected[i], msg)