diff --git a/src/mess/includes/bbc.h b/src/mess/includes/bbc.h
index 7f438ec7c66..43e4196ebc1 100644
--- a/src/mess/includes/bbc.h
+++ b/src/mess/includes/bbc.h
@@ -334,7 +334,7 @@ public:
 	DECLARE_WRITE_LINE_MEMBER(bbc_vsync);
 	DECLARE_READ_LINE_MEMBER(bbc_rxd_r) { return ( m_serproc_data & 0x40 ) ? m_rxd_rs423 : m_rxd_cass; }
 	DECLARE_READ_LINE_MEMBER(bbc_dcd_r) { return ( m_serproc_data & 0x40 ) ? 0 : m_dcd_cass; }
-	DECLARE_READ_LINE_MEMBER(bbc_cts_r) { return ( m_serproc_data & 0x40 ) ? m_cts_rs423 : 1; }
+	DECLARE_READ_LINE_MEMBER(bbc_cts_r) { return ( m_serproc_data & 0x40 ) ? m_cts_rs423 : 0; }
 	DECLARE_WRITE_LINE_MEMBER(bbc_rts_w);
 	DECLARE_WRITE_LINE_MEMBER(bbc_txd_w);
 
diff --git a/src/mess/machine/bbc.c b/src/mess/machine/bbc.c
index 62910d1604d..b393f476514 100644
--- a/src/mess/machine/bbc.c
+++ b/src/mess/machine/bbc.c
@@ -2091,7 +2091,7 @@ DRIVER_INIT_MEMBER(bbc_state,bbc)
 	m_rxd_cass = 0;
 	m_rxd_rs423 = 0;
 	m_dcd_cass = 0;
-	m_cts_rs423 = 1;
+	m_cts_rs423 = 0;
 	m_nr_high_tones = 0;
 	m_serproc_data = 0;
 	m_cass_out_enabled = 0;
@@ -2104,7 +2104,7 @@ DRIVER_INIT_MEMBER(bbc_state,bbcm)
 	m_rxd_cass = 0;
 	m_rxd_rs423 = 0;
 	m_dcd_cass = 0;
-	m_cts_rs423 = 1;
+	m_cts_rs423 = 0;
 	m_nr_high_tones = 0;
 	m_serproc_data = 0;
 	m_cass_out_enabled = 0;