diff --git a/NEWS b/NEWS
index 2017932b..704c1b0d 100644
--- a/NEWS
+++ b/NEWS
@@ -18,6 +18,7 @@ What's new in psycopg 2.7.2
   (:ticket:`#545`).
 - Fixed `~psycopg2.extras.ReplicationCursor.consume_stream()`
   *keepalive_interval* argument (:ticket:`#547`).
+- Fixed random `!SystemError` upon receiving abort signal (:ticket:`#551`).
 - `~psycopg2.errorcodes` map updated to PostgreSQL 10 beta 1.
 
 
diff --git a/psycopg/pqpath.c b/psycopg/pqpath.c
index 55720724..7e8c8e8b 100644
--- a/psycopg/pqpath.c
+++ b/psycopg/pqpath.c
@@ -1893,8 +1893,12 @@ pq_fetch(cursorObject *curs, int no_result)
     Dprintf("pq_fetch: pgstatus = %s", PQresStatus(pgstatus));
 
     /* backend status message */
-    Py_XDECREF(curs->pgstatus);
-    curs->pgstatus = conn_text_from_chars(curs->conn, PQcmdStatus(curs->pgres));
+    Py_CLEAR(curs->pgstatus);
+    if (!(curs->pgstatus = conn_text_from_chars(
+            curs->conn, PQcmdStatus(curs->pgres)))) {
+        ex = -1;
+        return ex;
+    }
 
     switch(pgstatus) {
 
diff --git a/tests/test_connection.py b/tests/test_connection.py
index f61b099d..d88e853a 100755
--- a/tests/test_connection.py
+++ b/tests/test_connection.py
@@ -26,6 +26,7 @@ import os
 import sys
 import time
 import threading
+import subprocess as sp
 from operator import attrgetter
 
 import psycopg2
@@ -33,7 +34,7 @@ import psycopg2.errorcodes
 from psycopg2 import extensions as ext
 
 from testutils import (
-    unittest, decorate_all_tests, skip_if_no_superuser,
+    script_to_py3, unittest, decorate_all_tests, skip_if_no_superuser,
     skip_before_postgres, skip_after_postgres, skip_before_libpq,
     ConnectingTestCase, skip_if_tpc_disabled, skip_if_windows, slow)
 
@@ -1516,6 +1517,61 @@ class PasswordLeakTestCase(ConnectingTestCase):
             "user=someone password=xxx host=localhost dbname=nosuch")
 
 
+class SignalTestCase(ConnectingTestCase):
+    @slow
+    def test_bug_551_returning(self):
+        # Raise an exception trying to decode 'id'
+        self._test_bug_551(query="""
+            INSERT INTO test551 (num) VALUES (%s) RETURNING id
+            """)
+
+    @slow
+    def test_bug_551_no_returning(self):
+        # Raise an exception trying to decode 'INSERT 0 1'
+        self._test_bug_551(query="""
+            INSERT INTO test551 (num) VALUES (%s)
+            """)
+
+    def _test_bug_551(self, query):
+        script = ("""\
+import os
+import sys
+import time
+import signal
+import threading
+
+import psycopg2
+
+def handle_sigabort(sig, frame):
+    sys.exit(1)
+
+def killer():
+    time.sleep(0.5)
+    os.kill(os.getpid(), signal.SIGABRT)
+
+signal.signal(signal.SIGABRT, handle_sigabort)
+
+conn = psycopg2.connect(%(dsn)r)
+
+cur = conn.cursor()
+
+cur.execute("create table test551 (id serial, num varchar(50))")
+
+t = threading.Thread(target=killer)
+t.daemon = True
+t.start()
+
+while True:
+    cur.execute(%(query)r, ("Hello, world!",))
+""" % {'dsn': dsn, 'query': query})
+
+        proc = sp.Popen([sys.executable, '-c', script_to_py3(script)],
+            stdout=sp.PIPE, stderr=sp.PIPE)
+        (out, err) = proc.communicate()
+        self.assertNotEqual(proc.returncode, 0)
+        self.assert_(not err, err)
+
+
 def test_suite():
     return unittest.TestLoader().loadTestsFromName(__name__)