diff --git a/wycheproof/aead.pl b/wycheproof/aead.pl
index b7c8cb0..f55b6ff 100644
--- a/wycheproof/aead.pl
+++ b/wycheproof/aead.pl
@@ -12,7 +12,7 @@ sub slurp ($fh) { local $/; <$fh> }
 
 sub usage ()
 {
-	say STDERR "Usage: $progname [-Fv] -x runner json_file ",
+	say STDERR "Usage: $progname [-Cv] -x runner json_file ",
 	    "[json_files ...]";
 	exit 1;
 }
@@ -22,7 +22,7 @@ sub main ()
 	my %opts;
 	my $rc = 0;
 
-	getopts("Fvx:", \%opts) && @ARGV > 0 or usage;
+	getopts("Cvx:", \%opts) && @ARGV > 0 or usage;
 	usage unless defined $opts{"x"};
 
 	for my $f (@ARGV) {
@@ -57,7 +57,7 @@ sub main ()
 					    "$test->{comment} [",
 					    join(",", $test->{flags}->@*),
 					    "]";
-					exit 1 if $opts{"F"};
+					exit 1 unless $opts{"C"};
 				}
 			}
 		}
diff --git a/wycheproof/mac.pl b/wycheproof/mac.pl
index 73875d8..308f196 100644
--- a/wycheproof/mac.pl
+++ b/wycheproof/mac.pl
@@ -12,7 +12,7 @@ sub slurp ($fh) { local $/; <$fh> }
 
 sub usage ()
 {
-	say STDERR "Usage: $progname [-Fv] -x runner json_file ",
+	say STDERR "Usage: $progname [-Cv] -x runner json_file ",
 	    "[json_files ...]";
 	exit 1;
 }
@@ -22,7 +22,7 @@ sub main ()
 	my %opts;
 	my $rc = 0;
 
-	getopts("Fvx:", \%opts) && @ARGV > 0 or usage;
+	getopts("Cvx:", \%opts) && @ARGV > 0 or usage;
 	usage unless defined $opts{"x"};
 
 	for my $f (@ARGV) {
@@ -53,7 +53,7 @@ sub main ()
 					    "$test->{comment} [",
 					    join(",", $test->{flags}->@*),
 					    "]";
-					exit 1 if $opts{"F"};
+					exit 1 unless $opts{"C"};
 				}
 			}
 		}