diff --git a/doc/src/install.rst b/doc/src/install.rst
index 674bbac8..4611537e 100644
--- a/doc/src/install.rst
+++ b/doc/src/install.rst
@@ -19,7 +19,8 @@ The current `!psycopg2` implementation supports:
 
 - Python 2 versions from 2.6 to 2.7
 - Python 3 versions from 3.1 to 3.5
-- PostgreSQL versions from 7.4 to 9.4
+- PostgreSQL server versions from 7.4 to 9.5
+- PostgreSQL client library version from 9.1
 
 .. _PostgreSQL: http://www.postgresql.org/
 .. _Python: http://www.python.org/
diff --git a/psycopg/pqpath.c b/psycopg/pqpath.c
index d7283d0c..d02cb708 100644
--- a/psycopg/pqpath.c
+++ b/psycopg/pqpath.c
@@ -1913,7 +1913,7 @@ pq_fetch(cursorObject *curs, int no_result)
         break;
 
     default:
-        /* PGRES_COPY_BOTH, PGRES_SINGLE_TUPLE, future statuses */
+        /* PGRES_SINGLE_TUPLE, future statuses */
         Dprintf("pq_fetch: got unsupported result: status = %d pgconn = %p",
             pgstatus, curs->conn);
         PyErr_Format(NotSupportedError,
diff --git a/psycopg/psycopg.h b/psycopg/psycopg.h
index 3174f309..82b4293c 100644
--- a/psycopg/psycopg.h
+++ b/psycopg/psycopg.h
@@ -26,6 +26,10 @@
 #ifndef PSYCOPG_H
 #define PSYCOPG_H 1
 
+#if PG_VERSION_NUM < 90100
+#error "Psycopg requires PostgreSQL client library (libpq) >= 9.1"
+#endif
+
 #define PY_SSIZE_T_CLEAN
 #include <Python.h>
 #include <libpq-fe.h>