diff --git a/c4emu.cpp b/c4emu.cpp
index 3718be77..a0dfcca3 100644
--- a/c4emu.cpp
+++ b/c4emu.cpp
@@ -1021,11 +1021,10 @@ void S9xSetC4 (uint8 byte, uint16 Address)
 					if (Memory.C4RAM[0x1f4d] != 0x0e)
 						printf("$7f4d=%02x, expected 0e for command 54 %02x\n", Memory.C4RAM[0x1f4d], Memory.C4RAM[0x1f4d]);
 				#endif
-					int64   b = (int64) READ_3WORD(Memory.C4RAM + 0x1f80);
-					int64   c = b << 40;
-					int64	a = SAR(c, 30);
-					a = SAR(c, 10);
+					int64	a = SAR((int64) READ_3WORD(Memory.C4RAM + 0x1f80) << 40, 40);
+					//printf("%08X%08X\n", (uint32) (a>>32), (uint32) (a&0xFFFFFFFF));
 					a *= a;
+					//printf("%08X%08X\n", (uint32) (a>>32), (uint32) (a&0xFFFFFFFF));
 					WRITE_3WORD(Memory.C4RAM + 0x1f83, a);
 					WRITE_3WORD(Memory.C4RAM + 0x1f86, (a >> 24));
 					break;