diff --git a/fuzz/common_fuzzer_corpus/sharpen_fuzzer-5806172036399104 b/fuzz/common_fuzzer_corpus/sharpen_fuzzer-5806172036399104
new file mode 100644
index 00000000..d019aac1
Binary files /dev/null and b/fuzz/common_fuzzer_corpus/sharpen_fuzzer-5806172036399104 differ
diff --git a/libvips/foreign/gifload.c b/libvips/foreign/gifload.c
index 0eec998c..d7cc4975 100644
--- a/libvips/foreign/gifload.c
+++ b/libvips/foreign/gifload.c
@@ -700,8 +700,14 @@ vips_foreign_load_gif_scan_extension( VipsForeignLoadGif *gif )
 static int
 vips_foreign_load_gif_set_header( VipsForeignLoadGif *gif, VipsImage *image )
 {
+	const gint64 total_height = (gint64) gif->file->SHeight * gif->n;
+	if ( total_height <= 0 || total_height > VIPS_MAX_COORD ) {
+		vips_error( "gifload", "%s",
+			_( "image size out of bounds" ) );
+		return( -1 );
+	}
 	vips_image_init_fields( image,
-		gif->file->SWidth, gif->file->SHeight * gif->n,
+		gif->file->SWidth, (int) total_height,
 		(gif->has_colour ? 3 : 1) + (gif->has_transparency ? 1 : 0),
 		VIPS_FORMAT_UCHAR, VIPS_CODING_NONE,
 		gif->has_colour ?