diff --git a/datemath/helpers.py b/datemath/helpers.py
index d3e5096..1a8af5f 100644
--- a/datemath/helpers.py
+++ b/datemath/helpers.py
@@ -168,23 +168,17 @@ def evaluate(expression, now, timeZone='UTC'):
     if debug: print('Expression: {0}'.format(expression))
     if debug: print('Now: {0}'.format(now))
     val = 0
-    for i, c in enumerate(expression):
+    i = 0
+    while i < len(expression):
         char = expression[i]
 
-        if i >= len(expression):
-            raise('Truncated datemath: {0}'.format(expression))
-
         if '/' in char:
-            # then we need to round up
+            # then we need to round
             next = str(expression[i+1])
-
-            roundUp = True            
+            i += 1
             now = roundDate(now, unitMap(next).rstrip('s'), timeZone)
 
         elif char == '+' or char == '-':
-            if i >= len(expression):
-                raise DateMathException('Truncated datemath: {0}'.format(expression))
-
             val = 0
 
             try:
@@ -202,7 +196,7 @@ def evaluate(expression, now, timeZone='UTC'):
         elif re.match('[a-zA-Z]+', char):
             now = calculate(now, val, unitMap(char))
         
-        i = i+1
+        i += 1
     if debug: print("Fin: {0}".format(now))
     if debug: print('\n\n')
     return now
diff --git a/tests.py b/tests.py
index d851e9f..a5d8b47 100644
--- a/tests.py
+++ b/tests.py
@@ -57,6 +57,10 @@ def testParse(self):
         self.assertEqual(dm('/M+2d').format(iso8601), arrow.utcnow().floor('month').replace(days=+2).format(iso8601))
         self.assertEqual(dm('now/w+2d-2h').format(iso8601), arrow.utcnow().floor('week').replace(days=+2, hours=-2).format(iso8601))
         self.assertEqual(dm('now/M+1w-2h+10s').format(iso8601), arrow.utcnow().floor('month').replace(weeks=+1, hours=-2, seconds=+10).format(iso8601))
+        self.assertEqual(dm('now-1d/d').format(iso8601), arrow.utcnow().replace(days=-1).floor('day').format(iso8601))
+        self.assertEqual(dm('now+1d/d').format(iso8601), arrow.utcnow().replace(days=1).floor('day').format(iso8601))
+        self.assertEqual(dm('now-10d/d').format(iso8601), arrow.utcnow().replace(days=-10).floor('day').format(iso8601))
+        self.assertEqual(dm('now+10d/d').format(iso8601), arrow.utcnow().replace(days=10).floor('day').format(iso8601))
         
 
         # future