diff --git a/can/io/blf.py b/can/io/blf.py
index 7d944a846..deefd4736 100644
--- a/can/io/blf.py
+++ b/can/io/blf.py
@@ -530,7 +530,10 @@ def _add_object(self, obj_type, data, timestamp=None):
         if timestamp is None:
             timestamp = self.stop_timestamp or time.time()
         if self.start_timestamp is None:
-            self.start_timestamp = timestamp
+            # Save start timestamp using the same precision as the BLF format
+            # Truncating to milliseconds to avoid rounding errors when calculating
+            # the timestamp difference
+            self.start_timestamp = int(timestamp * 1000) / 1000
         self.stop_timestamp = timestamp
         timestamp = int((timestamp - self.start_timestamp) * 1e9)
         header_size = OBJ_HEADER_BASE_STRUCT.size + OBJ_HEADER_V1_STRUCT.size
diff --git a/test/data/example_data.py b/test/data/example_data.py
index 592556926..b78420e4e 100644
--- a/test/data/example_data.py
+++ b/test/data/example_data.py
@@ -160,7 +160,7 @@ def sort_messages(messages):
 
 TEST_MESSAGES_ERROR_FRAMES = sort_messages(
     [
-        Message(is_error_frame=True),
+        Message(is_error_frame=True, timestamp=TEST_TIME),
         Message(is_error_frame=True, timestamp=TEST_TIME + 0.170),
         Message(is_error_frame=True, timestamp=TEST_TIME + 17.157),
     ]