diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index 9ba0f08582f0..ba66bb7fc1ca 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -273,7 +273,7 @@ static void new_line_csv(struct perf_stat_config *config, void *ctx)
 
 	fputc('\n', os->fh);
 	if (os->prefix)
-		fprintf(os->fh, "%s%s", os->prefix, config->csv_sep);
+		fprintf(os->fh, "%s", os->prefix);
 	aggr_printout(config, os->evsel, os->id, os->nr);
 	for (i = 0; i < os->nfields; i++)
 		fputs(config->csv_sep, os->fh);