diff --git a/scripts/tophat_fft.pl b/scripts/tophat_fft.pl
index 5f30ff2..4881bcf 100755
--- a/scripts/tophat_fft.pl
+++ b/scripts/tophat_fft.pl
@@ -65,7 +65,7 @@ foreach (@tophat_list) {
     #   proper output.
     my $φdiff = atan2($V,$U);
 
-    wcols $f,$φdiff,"analyses/tables/tophat_φdiff";
+    wcols $f,$φdiff,"analyses/tables/tophat_φdiff${tophat_count}.tab";
 
     my $offset = $φdiff/($_2π*$f);