diff --git a/scripts/cov.py b/scripts/cov.py
index 1df42ce7..a69e33c0 100755
--- a/scripts/cov.py
+++ b/scripts/cov.py
@@ -169,7 +169,12 @@ class RFrac(co.namedtuple('RFrac', 'a,b')):
         return '%11s' % (self,)
 
     def notes(self):
-        t = self.a.x/self.b.x if self.b.x else 1.0
+        if self.b.x == 0 and self.a.x == 0:
+            t = 1.0
+        elif self.b.x == 0:
+            t = mt.copysign(mt.inf, self.a.x)
+        else:
+            t = self.a.x / self.b.x
         return ['∞%' if t == +mt.inf
                 else '-∞%' if t == -mt.inf
                 else '%.1f%%' % (100*t)]
diff --git a/scripts/csv.py b/scripts/csv.py
index ac81e57d..c6d52e13 100755
--- a/scripts/csv.py
+++ b/scripts/csv.py
@@ -261,7 +261,12 @@ class RFrac(co.namedtuple('RFrac', 'a,b')):
         return '%11s' % (self,)
 
     def notes(self):
-        t = self.a.x/self.b.x if self.b.x else 1.0
+        if self.b.x == 0 and self.a.x == 0:
+            t = 1.0
+        elif self.b.x == 0:
+            t = mt.copysign(mt.inf, self.a.x)
+        else:
+            t = self.a.x / self.b.x
         return ['∞%' if t == +mt.inf
                 else '-∞%' if t == -mt.inf
                 else '%.1f%%' % (100*t)]
@@ -735,8 +740,10 @@ class RExpr:
 
         def eval(self, fields={}):
             v = RFrac(self.a.eval(fields))
-            if not float(v.b):
+            if not float(v.b) and not float(v.a):
                 return RFloat(1)
+            elif not float(v.b):
+                return RFloat(mt.copysign(mt.inf, float(v.a)))
             else:
                 return RFloat(float(v.a) / float(v.b))