diff --git a/src/video/vid_ega.c b/src/video/vid_ega.c
index 5a552ab6d..e96bd827c 100644
--- a/src/video/vid_ega.c
+++ b/src/video/vid_ega.c
@@ -149,6 +149,7 @@ ega_out(uint16_t addr, uint8_t val, void *priv)
             ega->vres           = !(val & 0x80);
             ega->pallook        = ega->vres ? pallook16 : pallook64;
             ega->vidclock       = val & 4;
+            pclog("clock = %01X\n", (val & 0x0c) >> 2);
             ega->miscout        = val;
             ega->overscan_color = ega->vres ? pallook16[ega->attrregs[0x11] & 0x0f] :
                                               pallook64[ega->attrregs[0x11] & 0x3f];
@@ -603,7 +604,22 @@ ega_recalctimings(ega_t *ega)
     ega->linedbl  = ega->crtc[9] & 0x80;
     ega->rowcount = ega->crtc[9] & 0x1f;
 
-    if (ega_type == EGA_TYPE_COMPAQ) {
+    if (ega->actual_type == EGA_SUPEREGA) {
+        switch ((ega->miscout >> 2) & 0x03) {
+            case 0x00:
+                crtcconst = (cpuclock / 16257000.0 * (double) (1ULL << 32));
+                break;
+            case 0x01:
+                crtcconst = (cpuclock / (157500000.0 / 11.0) * (double) (1ULL << 32));
+                break;
+            default:
+            case 0x02: case 0x03:
+                crtcconst = (cpuclock / 25110000.0 * (double) (1ULL << 32));
+                break;
+        }
+
+        crtcconst *= mdiv;
+    } else if (ega_type == EGA_TYPE_COMPAQ) {
         color = (ega->miscout & 1);
         clksel = ((ega->miscout & 0xc) >> 2);