diff --git a/rdflib/plugins/serializers/patch.py b/rdflib/plugins/serializers/patch.py
index 58928c6a0..cddc68b49 100644
--- a/rdflib/plugins/serializers/patch.py
+++ b/rdflib/plugins/serializers/patch.py
@@ -65,7 +65,7 @@ def serialize(
         def write_header():
             stream.write(f"H id <{header_id}> .\n".encode(encoding, "replace"))
             if header_prev:
-                stream.write(f"H prev <{header_prev}>\n".encode(encoding, "replace"))
+                stream.write(f"H prev <{header_prev}> .\n".encode(encoding, "replace"))
             stream.write("TX .\n".encode(encoding, "replace"))
 
         def write_triples(contexts, op_code, use_passed_contexts=False):