diff --git a/src/emu/cpu/tms34010/34010gfx.c b/src/emu/cpu/tms34010/34010gfx.c
index c668f9da16e..929ea86124e 100644
--- a/src/emu/cpu/tms34010/34010gfx.c
+++ b/src/emu/cpu/tms34010/34010gfx.c
@@ -1427,11 +1427,16 @@ if ((daddr & (BITS_PER_PIXEL - 1)) != 0) osd_printf_debug("PIXBLT_R%d with odd d
 					if (!TRANSPARENCY || pixel != 0)
 						dstword = (dstword & ~dstmask) | pixel;
 
+					#if (BITS_PER_PIXEL<16)
 					/* update the source */
 					srcmask = srcmask >> BITS_PER_PIXEL;
 
 					/* update the destination */
 					dstmask = dstmask >> BITS_PER_PIXEL;
+					#else
+					srcmask = 0;
+					dstmask = 0;
+					#endif
 				}
 
 				/* write the result */
@@ -1469,11 +1474,16 @@ if ((daddr & (BITS_PER_PIXEL - 1)) != 0) osd_printf_debug("PIXBLT_R%d with odd d
 					if (!TRANSPARENCY || pixel != 0)
 						dstword = (dstword & ~dstmask) | pixel;
 
+					#if (BITS_PER_PIXEL<16)
 					/* update the source */
 					srcmask = srcmask >> BITS_PER_PIXEL;
 
 					/* update the destination */
 					dstmask = dstmask >> BITS_PER_PIXEL;
+					#else
+					srcmask = 0;
+					dstmask = 0;
+					#endif
 				}
 
 				/* write the result */
@@ -1507,11 +1517,16 @@ if ((daddr & (BITS_PER_PIXEL - 1)) != 0) osd_printf_debug("PIXBLT_R%d with odd d
 					if (!TRANSPARENCY || pixel != 0)
 						dstword = (dstword & ~dstmask) | pixel;
 
+					#if (BITS_PER_PIXEL<16)
 					/* update the source */
 					srcmask = srcmask >> BITS_PER_PIXEL;
 
 					/* update the destination */
 					dstmask = dstmask >> BITS_PER_PIXEL;
+					#else
+					srcmask = 0;
+					dstmask = 0;
+					#endif
 				}
 
 				/* write the result */