diff --git a/lib/evaluation_details.rb b/lib/evaluation_details.rb
index c6a1580..8141c5f 100644
--- a/lib/evaluation_details.rb
+++ b/lib/evaluation_details.rb
@@ -21,7 +21,7 @@ def initialize(config_sync_time, init_time, reason)
       @config_sync_time = config_sync_time
       @init_time = init_time
       @reason = reason
-      @server_time = (Time.now.to_i * 1000).to_s
+      @server_time = (Time.now.to_f * 1000).to_i.to_s
     end
 
     def self.unsupported(config_sync_time, init_time)
diff --git a/test/evaluation_details_precision_test.rb b/test/evaluation_details_precision_test.rb
new file mode 100644
index 0000000..047065d
--- /dev/null
+++ b/test/evaluation_details_precision_test.rb
@@ -0,0 +1,19 @@
+require 'minitest/autorun'
+require 'minitest/mock'
+require_relative '../lib/evaluation_details'
+
+class EvaluationDetailsPrecisionTest < Minitest::Test
+  def test_server_time_preserves_milliseconds_as_a_string
+    [
+      [0, '1631638014000'],
+      [811_999, '1631638014811'],
+      [999_999, '1631638014999'],
+    ].each do |microseconds, expected|
+      Time.stub(:now, Time.at(1_631_638_014, microseconds)) do
+        details = Statsig::EvaluationDetails.new(1, 2, Statsig::EvaluationReason::NETWORK)
+
+        assert_equal(expected, details.server_time)
+      end
+    end
+  end
+end