diff --git a/build_tools/diff_profiles.fish b/build_tools/diff_profiles.fish
old mode 100644
new mode 100755
index d0c5ab38b..7e1d2bf15
--- a/build_tools/diff_profiles.fish
+++ b/build_tools/diff_profiles.fish
@@ -5,6 +5,12 @@
 #
 # Usage: ./diff_profiles.fish profile1.log profile2.log > profile_diff.log
 
+if test (count $argv) -ne 2;
+    echo "Incorrect number of arguments."
+    echo "Usage: "(status filename)" profile1.log profile2.log"
+    exit 1
+end
+
 set -l profile1 (cat $argv[1])
 set -l profile2 (cat $argv[2])
 
@@ -15,13 +21,13 @@ while set -l next_line_no (math $line_no + 1) && set -q profile1[$next_line_no]
     set -l line1 $profile1[$line_no]
     set -l line2 $profile2[$line_no]
 
-    if not string match -qr '^\d+\t\d+' $line1
+    if not string match -qr '^\s*\d+\s+\d+' $line1
         echo $line1
         continue
     end
 
-    set -l results1 (string match -r '^(\d+)\t(\d+)\s+(.*)' $line1)
-    set -l results2 (string match -r '^(\d+)\t(\d+)\s+(.*)' $line2)
+    set -l results1 (string match -r '^\s*(\d+)\s+(\d+)\s+(.*)' $line1)
+    set -l results2 (string match -r '^\s*(\d+)\s+(\d+)\s+(.*)' $line2)
 
     # times from both files
     set -l time1 $results1[2..3]
@@ -42,5 +48,5 @@ while set -l next_line_no (math $line_no + 1) && set -q profile1[$next_line_no]
     set diff[1] (math $time1[1] - $time2[1])
     set diff[2] (math $time1[2] - $time2[2])
 
-    echo $diff[1] $diff[2] $remainder1
+    printf '%10d %10d %s\n' $diff[1] $diff[2] $remainder1
 end