diff --git a/output/output_text.c b/output/output_text.c
index 6e2d4f08..03eac777 100644
--- a/output/output_text.c
+++ b/output/output_text.c
@@ -194,7 +194,11 @@ static int data_bits(struct output *o, char *data_in, uint64_t length_in,
 	ctx = o->internal;
 	max_linelen = MAX_PROBENAME_LEN + 3 + ctx->samples_per_line
 			+ ctx->samples_per_line / 8;
-	outsize = (1 + (length_in / ctx->unitsize) / ctx->samples_per_line)
+        /*
+         * Calculate space needed for probes. Set aside 512 bytes for
+         * extra output, e.g. trigger.
+         */
+	outsize = 512 + (1 + (length_in / ctx->unitsize) / ctx->samples_per_line)
             * (ctx->num_enabled_probes * max_linelen);
 
 	if (!(outbuf = calloc(1, outsize + 1)))