diff --git a/libvips/resample/shrinkv.c b/libvips/resample/shrinkv.c
index 2b91737a..97ef418d 100644
--- a/libvips/resample/shrinkv.c
+++ b/libvips/resample/shrinkv.c
@@ -199,12 +199,13 @@ vips_shrinkv_add_line( VipsShrinkv *shrink, VipsShrinkvSequence *seq,
 
 /* Integer average. 
  */
-#define IAVG( TYPE ) { \
+#define IAVG( TYPE, BTYPE ) { \
 	int * restrict sum = (int *) seq->sum; \
 	TYPE * restrict q = (TYPE *) out; \
 	\
 	for( x = 0; x < sz; x++ ) \
-		q[x] = (sum[x] + shrink->vshrink / 2) / shrink->vshrink; \
+		q[x] = ((BTYPE) sum[x] + shrink->vshrink / 2) / \
+			shrink->vshrink; \
 } 
 
 /* Float average. 
@@ -234,17 +235,17 @@ vips_shrinkv_write_line( VipsShrinkv *shrink, VipsShrinkvSequence *seq,
 	VipsPel *out = VIPS_REGION_ADDR( or, left, top ); 
 	switch( resample->in->BandFmt ) {
 	case VIPS_FORMAT_UCHAR: 	
-		IAVG( unsigned char ); break;
+		IAVG( unsigned char, int ); break;
 	case VIPS_FORMAT_CHAR: 	
-		IAVG( char ); break; 
+		IAVG( char, int ); break; 
 	case VIPS_FORMAT_USHORT: 
-		IAVG( unsigned short ); break;
+		IAVG( unsigned short, int ); break;
 	case VIPS_FORMAT_SHORT: 	
-		IAVG( short ); break; 
+		IAVG( short, int ); break; 
 	case VIPS_FORMAT_UINT: 	
-		IAVG( unsigned int ); break; 
+		IAVG( unsigned int, int ); break; 
 	case VIPS_FORMAT_INT: 	
-		IAVG( int );  break; 
+		IAVG( int, gint64 );  break; 
 	case VIPS_FORMAT_FLOAT: 	
 		FAVG( float ); break; 
 	case VIPS_FORMAT_DOUBLE: