diff --git a/src/sample.c b/src/sample.c
index f032ec4bb..7b636129a 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -2150,11 +2150,11 @@ static int sample_conv_be2hex_check(struct arg *args, struct sample_conv *conv,
  */
 static int sample_conv_be2hex(const struct arg *args, struct sample *smp, void *private)
 {
-	struct buffer *trash = get_trash_chunk_sz(smp->data.u.str.data);
+	struct buffer *trash = get_trash_chunk_sz(smp->data.u.str.data * 2);
 	int chunk_size = args[1].data.sint;
 	const int last = args[2].data.sint ? smp->data.u.str.data - chunk_size + 1 : smp->data.u.str.data;
 	int i;
-	int max_size;
+	size_t max_size;
 	int ptr = 0;
 	unsigned char c;
 
@@ -2163,7 +2163,9 @@ static int sample_conv_be2hex(const struct arg *args, struct sample *smp, void *
 	trash->data = 0;
 	if (args[0].data.str.data == 0 && args[2].data.sint == 0)
 		chunk_size = smp->data.u.str.data;
-	max_size = trash->size - 2 * chunk_size;
+	if (2 * (size_t)chunk_size > trash->size)
+		return 0;
+	max_size = trash->size - 2 * (size_t)chunk_size;
 
 	while (ptr < last && trash->data <= max_size) {
 		if (ptr) {