diff --git a/converter/ps2_usb/config.h b/converter/ps2_usb/config.h
index 6fbf136..51cd271 100644
--- a/converter/ps2_usb/config.h
+++ b/converter/ps2_usb/config.h
@@ -39,6 +39,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 )
 
 
+/* legacy keymap support */
+#define USE_LEGACY_KEYMAP
+
+
 #ifdef PS2_USE_USART
 #if defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)
 /* XCK for clock line and RXD for data line */
diff --git a/keyboard/IIgs/config.h b/keyboard/IIgs/config.h
index 842e404..bc8bf75 100644
--- a/keyboard/IIgs/config.h
+++ b/keyboard/IIgs/config.h
@@ -56,4 +56,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define LAYER_SEND_FN_TERM 300
 
 
+/* legacy keymap support */
+#define USE_LEGACY_KEYMAP
+
+
 #endif