diff --git a/.ruby-version b/.ruby-version
new file mode 100644
index 0000000..73462a5
--- /dev/null
+++ b/.ruby-version
@@ -0,0 +1 @@
+2.5.1
diff --git a/lib/har/archive.rb b/lib/har/archive.rb
index d5417e7..18ea24f 100644
--- a/lib/har/archive.rb
+++ b/lib/har/archive.rb
@@ -72,6 +72,14 @@ def entries
       @entries ||= raw_entries.map { |e| Entry.new(e) }
     end
 
+    def entries_before(time)
+      raise TypeError, "expected Time" unless time.is_a?(Time)
+      entries.select do |entry|
+        return false unless entry.time
+        entry.started_date_time + entry.time / 1000.0 <= time
+      end
+    end
+
     # create a new archive by merging this and another archive
 
     def merge(other)
diff --git a/lib/har/page.rb b/lib/har/page.rb
index e615f27..09f57ac 100644
--- a/lib/har/page.rb
+++ b/lib/har/page.rb
@@ -16,7 +16,7 @@ def entries_before(time)
       raise TypeError, "expected Time" unless time.is_a?(Time)
       entries.select do |entry|
         return false unless entry.time
-        entry.started_date_time + entry.time / 1000.0 < time
+        entry.started_date_time + entry.time / 1000.0 <= time
       end
     end
   end
diff --git a/spec/har/archive_spec.rb b/spec/har/archive_spec.rb
index 689a755..d82eadc 100644
--- a/spec/har/archive_spec.rb
+++ b/spec/har/archive_spec.rb
@@ -152,5 +152,22 @@ module HAR
       end
     end
 
+    describe "#entries_before" do
+      let(:archive) { Archive.from_file(google_path) }
+
+      it "requires a DateTime" do
+        expect { archive.entries_before("a string") }.to raise_error(TypeError)
+      end
+
+      it "filters entries that responded before the specified time" do
+        time = archive.pages.first.started_date_time + 0.250
+        entries = archive.entries_before(time)
+        entries.each do |entry|
+          (entry.started_date_time + entry.time / 1000.to_f).should < time
+        end
+
+        entries.length.should < archive.entries.length
+      end
+    end
   end # Archive
 end # HAR
diff --git a/spec/har/page_spec.rb b/spec/har/page_spec.rb
index ea10c56..379db36 100644
--- a/spec/har/page_spec.rb
+++ b/spec/har/page_spec.rb
@@ -30,6 +30,8 @@ module HAR
           entries.each do |entry|
             (entry.started_date_time + entry.time / 1000.to_f).should < time
           end
+
+          entries.length.should < page.entries.length
         end
       end
     end