diff --git a/lib/prometheus/client/data_stores/direct_file_store.rb b/lib/prometheus/client/data_stores/direct_file_store.rb
index 717d8d5c..7bb5c1f4 100644
--- a/lib/prometheus/client/data_stores/direct_file_store.rb
+++ b/lib/prometheus/client/data_stores/direct_file_store.rb
@@ -257,8 +257,7 @@ def all_values
             with_file_lock do
               @positions.map do |key, pos|
                 @f.seek(pos)
-                value = @f.read(8).unpack('d')[0]
-                timestamp = @f.read(8).unpack('d')[0]
+                value, timestamp = @f.read(16).unpack('dd')
                 [key, value, timestamp]
               end
             end