diff --git a/src/mame/video/n64.c b/src/mame/video/n64.c
index c926dad6ed3..08668350816 100644
--- a/src/mame/video/n64.c
+++ b/src/mame/video/n64.c
@@ -1800,7 +1800,7 @@ void N64::RDP::Triangle::compute_cvg_noflip(INT32* majorx, INT32* minorx, INT32*
 
 	if (length < 0) return;
 
-	memset(&m_rdp->Spans[scanline].m_cvg[purgestart], 0, (length + 1) << 2);
+	memset(&m_rdp->Spans[scanline].m_cvg[purgestart], 0, (length + 1) << 1);
 
 	for(int i = 0; i < 4; i++)
 	{
@@ -1873,7 +1873,7 @@ void N64::RDP::Triangle::compute_cvg_flip(INT32* majorx, INT32* minorx, INT32* m
 
 	if (length < 0) return;
 
-	memset(&m_rdp->Spans[scanline].m_cvg[purgestart], 0, (length + 1) << 2);
+	memset(&m_rdp->Spans[scanline].m_cvg[purgestart], 0, (length + 1) << 1);
 
 	for(int i = 0; i < 4; i++)
 	{
diff --git a/src/mame/video/rdpspn16.h b/src/mame/video/rdpspn16.h
index 051289cd481..2192f7fe2fb 100644
--- a/src/mame/video/rdpspn16.h
+++ b/src/mame/video/rdpspn16.h
@@ -58,7 +58,7 @@ class Span
 		SpanParam m_a;
 		SpanParam m_z;
 
-		UINT16 m_cvg[RDP_CVG_SPAN_MAX];
+		UINT16 m_cvg[RDP_CVG_SPAN_MAX+32];
 
 	private:
 		void RGBAZClip(int sr, int sg, int sb, int sa, int *sz);