diff --git a/src/xpdev/xpbeep.c b/src/xpdev/xpbeep.c
index 3f6cc207658742f3bfddaf9f76388e58023525ef..df7cf1f542ca81fa6760dba6f933c62cd57e6896 100644
--- a/src/xpdev/xpbeep.c
+++ b/src/xpdev/xpbeep.c
@@ -422,7 +422,7 @@ BOOL xptone(double freq, DWORD duration, enum WAVE_SHAPE shape)
 
 	/* Prepare for next note */
 	curr_wh=1-curr_wh;
-	memset(wave[curr_wh], 128, sizeof(wave));	/* Ensure that if silence DOES timeout, you still get silence */
+	memset(wave[curr_wh], 128, sizeof(wave[0]));	/* Ensure that if silence DOES timeout, you still get silence */
 	wh=&wh_bufs[curr_wh];
 	waveOutWrite(waveOut, wh, sizeof(wh_bufs[0]));