diff --git a/tests/summarize.sh b/tests/summarize.sh
index 98a2e05d..e5aad1d2 100644
--- a/tests/summarize.sh
+++ b/tests/summarize.sh
@@ -1,5 +1,5 @@
 # summarize.sh: extracts results of failed tests
-# (C) 2015 magicant
+# (C) 2015-2018 magicant
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -25,6 +25,12 @@ printf '=============\n\n'
 passed=0 failed=0 skipped=0
 
 for result_file do
+    # The "grep" command is generally faster than repeated "read" built-in.
+    if [ "$(grep -cE '^%%% (FAIL|SKIPP)ED:' "$result_file")" -eq 0 ]; then
+	passed="$((passed + $(grep -c '^%%% PASSED:' "$result_file")))"
+	continue
+    fi
+
     log=''
     while IFS= read -r line; do
 	log="$log