diff --git a/src/include/86box/vid_ogc.h b/src/include/86box/vid_ogc.h
index 839769e69..efafb180e 100644
--- a/src/include/86box/vid_ogc.h
+++ b/src/include/86box/vid_ogc.h
@@ -23,6 +23,7 @@
 
 typedef struct ogc_t {
     cga_t cga;
+    uint16_t ctrl_addr;
     /* unused in OGC, required for M19 video card structure idiom */
     uint8_t  ctrl_3dd;
     uint8_t  ctrl_3de;
diff --git a/src/machine/m_xt_olivetti.c b/src/machine/m_xt_olivetti.c
index b13db6bf9..817b0d0cc 100644
--- a/src/machine/m_xt_olivetti.c
+++ b/src/machine/m_xt_olivetti.c
@@ -2038,6 +2038,8 @@ m19_vid_init(m19_vid_t *vid)
         vid->ogc.mono_display = 0;
     else
         vid->ogc.mono_display = 1;
+
+    vid->ogc.ctrl_addr = 0x3db;
     /* OGC emulation part end */
 
     /* Plantronics emulation part begin*/
diff --git a/src/video/vid_ogc.c b/src/video/vid_ogc.c
index c3073898d..9ac94169c 100644
--- a/src/video/vid_ogc.c
+++ b/src/video/vid_ogc.c
@@ -97,11 +97,14 @@ ogc_out(uint16_t addr, uint8_t val, void *priv)
             cga_out(addr, val, &ogc->cga);
             break;
 
+        case 0x3db:
         case 0x3de:
-            /* set control register */
-            ogc->ctrl_3de = val;
-            /* select 1st or 2nd 16k vram block to be used */
-            ogc->base = (val & 0x08) ? 0x4000 : 0;
+            if (addr == ogc->ctrl_addr) {
+                /* set control register */
+                ogc->ctrl_3de = val;
+                /* select 1st or 2nd 16k vram block to be used */
+                ogc->base = (val & 0x08) ? 0x4000 : 0;
+            }
             break;
 
         default:
@@ -622,6 +625,8 @@ ogc_init(UNUSED(const device_t *info))
     else
         ogc->mono_display = 1;
 
+    ogc->ctrl_addr = 0x3de;
+
     return ogc;
 }