diff --git a/scd/apdu.h b/scd/apdu.h
index 1392aab71..89df45cb8 100644
--- a/scd/apdu.h
+++ b/scd/apdu.h
@@ -31,6 +31,7 @@ enum {
   SW_EOF_REACHED    = 0x6282,
   SW_TERM_STATE     = 0x6285, /* Selected file is in termination state.  */
   SW_EEPROM_FAILURE = 0x6581,
+  SW_ACK_TIMEOUT    = 0x6600, /* OpenPGPcard: Ack timeout.  */
   SW_WRONG_LENGTH   = 0x6700,
   SW_SM_NOT_SUP     = 0x6882, /* Secure Messaging is not supported.  */
   SW_CC_NOT_SUP     = 0x6884, /* Command Chaining is not supported.  */
diff --git a/scd/iso7816.c b/scd/iso7816.c
index 758de5b48..a9cd73014 100644
--- a/scd/iso7816.c
+++ b/scd/iso7816.c
@@ -67,6 +67,7 @@ map_sw (int sw)
     case SW_EEPROM_FAILURE: ec = GPG_ERR_HARDWARE; break;
     case SW_TERM_STATE:     ec = GPG_ERR_OBJ_TERM_STATE; break;
     case SW_WRONG_LENGTH:   ec = GPG_ERR_INV_VALUE; break;
+    case SW_ACK_TIMEOUT:    ec = GPG_ERR_TIMEOUT; break;
     case SW_SM_NOT_SUP:     ec = GPG_ERR_NOT_SUPPORTED; break;
     case SW_CC_NOT_SUP:     ec = GPG_ERR_NOT_SUPPORTED; break;
     case SW_CHV_WRONG:      ec = GPG_ERR_BAD_PIN; break;