diff --git a/ext/pg_connection.c b/ext/pg_connection.c
index c8b71d67b..4243e674b 100644
--- a/ext/pg_connection.c
+++ b/ext/pg_connection.c
@@ -568,13 +568,16 @@ static VALUE
 pgconn_reset_start2( VALUE self, VALUE conninfo )
 {
 	t_pg_connection *this = pg_get_connection( self );
+	/* Ensure conninfo is a valid C string before closing the connection. */
+	char *p_conninfo = StringValueCStr(conninfo);
 
 	/* Close old connection */
 	pgconn_close_socket_io( self );
 	PQfinish( this->pgconn );
+	this->pgconn = NULL; /* Ensure no double free can happen. */
 
 	/* Start new connection */
-	this->pgconn = gvl_PQconnectStart( StringValueCStr(conninfo) );
+	this->pgconn = gvl_PQconnectStart( p_conninfo );
 
 	if( this->pgconn == NULL )
 		rb_raise(rb_ePGerror, "PQconnectStart() unable to allocate PGconn structure");
diff --git a/spec/pg/connection_spec.rb b/spec/pg/connection_spec.rb
index fdae1b2b7..d9348c844 100644
--- a/spec/pg/connection_spec.rb
+++ b/spec/pg/connection_spec.rb
@@ -1871,6 +1871,11 @@
 		end.to raise_error(PG::Error)
 	end
 
+	it "reset with invalid conninfo doesn't close the connection" do
+		expect{ @conn.send(:reset_start2, "\0") }.to raise_error(ArgumentError)
+		expect( @conn.exec("SELECT 1").values ).to eq([["1"]])
+	end
+
 
 	it "closes the IO fetched from #socket_io when the connection is closed", :without_transaction do
 		conn = PG.connect( @conninfo )