diff --git a/hardware/asix-sigma/asix-sigma.c b/hardware/asix-sigma/asix-sigma.c
index c44bae7a..7e4b3caa 100644
--- a/hardware/asix-sigma/asix-sigma.c
+++ b/hardware/asix-sigma/asix-sigma.c
@@ -1073,13 +1073,20 @@ static int download_capture(struct sr_dev_inst *sdi)
 {
 	struct dev_context *devc = sdi->priv;
 	const int chunks_per_read = 32;
-	unsigned char buf[chunks_per_read * CHUNK_SIZE];
+	struct sigma_dram_line *dram_line;
+	unsigned char *buf;
 	int bufsz, i, numchunks, newchunks;
 	uint32_t stoppos, triggerpos;
 	int triggerchunk, chunks_downloaded;
 	struct sr_datafeed_packet packet;
 	uint8_t modestatus;
 
+	dram_line = g_try_malloc0(chunks_per_read * sizeof(*dram_line));
+	if (!dram_line)
+		return FALSE;
+
+	buf = (unsigned char *)dram_line;
+
 	sr_info("Downloading sample data.");
 
 	/* Stop acquisition. */
@@ -1143,6 +1150,8 @@ static int download_capture(struct sr_dev_inst *sdi)
 
 	dev_acquisition_stop(sdi, sdi);
 
+	g_free(dram_line);
+
 	return TRUE;
 }
 
diff --git a/hardware/asix-sigma/asix-sigma.h b/hardware/asix-sigma/asix-sigma.h
index 19330643..87c92fb7 100644
--- a/hardware/asix-sigma/asix-sigma.h
+++ b/hardware/asix-sigma/asix-sigma.h
@@ -76,6 +76,25 @@ enum sigma_read_register {
 
 #define CHUNK_SIZE		1024
 
+/*
+ * The entire ASIX Sigma DRAM is an array of struct sigma_dram_line[1024];
+ */
+
+/* One "DRAM cluster" contains a timestamp and 7 samples, 16b total. */
+struct sigma_dram_cluster {
+	uint8_t		timestamp_lo;
+	uint8_t		timestamp_hi;
+	struct {
+		uint8_t	sample_hi;
+		uint8_t	sample_lo;
+	}		samples[7];
+};
+
+/* One "DRAM line" contains 64 "DRAM clusters", 1024b total. */
+struct sigma_dram_line {
+	struct sigma_dram_cluster	cluster[64];
+};
+
 struct clockselect_50 {
 	uint8_t async;
 	uint8_t fraction;