diff --git a/redis-timeseries.rb b/redis-timeseries.rb
index fd01c0d..4c0e895 100644
--- a/redis-timeseries.rb
+++ b/redis-timeseries.rb
@@ -104,7 +104,7 @@ def seek(time)
                     break
                 end
                 # Already at the end of the string but still no luck?
-                return len+1 if range_end = len
+                return len+1 if range_end == len
                 # We need to enlrange the range, it is interesting to note
                 # that we take the enlarged value: likely other time series
                 # will be the same size on average.