diff --git a/t/10_baseline_ipv4_http.t b/t/10_baseline_ipv4_http.t
index aa52f3834..4dd38e805 100755
--- a/t/10_baseline_ipv4_http.t
+++ b/t/10_baseline_ipv4_http.t
@@ -30,6 +30,8 @@ my $socket_errors='(e|E)rror|FIXME|\.\/testssl\.sh: line |(f|F)atal|(c|C)ommand
 my $openssl_errors='(e|E)rror|FIXME|(f|F)atal|\.\/testssl\.sh: line |Oops|s_client connect problem|(c|C)ommand not found';
 my $json_errors='(id".*:\s"scanProblem"|severity".*:\s"FATAL"|"Scan interrupted")';
 
+# useful against "failed to flush stdout" messages
+STDOUT->autoflush(1);
 
 die "Unable to open $prg" unless -f $prg;
 
diff --git a/t/12_diff_opensslversions.t b/t/12_diff_opensslversions.t
index eb4d66824..b848dc00f 100755
--- a/t/12_diff_opensslversions.t
+++ b/t/12_diff_opensslversions.t
@@ -23,6 +23,9 @@ my @args="";
 # that can be done better but I am a perl n00b ;-)
 my $os=`perl -e 'print "$^O";'`;
 
+# useful against "failed to flush stdout" messages
+STDOUT->autoflush(1);
+
 die "Unable to open $prg" unless -f $prg;
 die "Unable to open $distro_openssl" unless -f $distro_openssl;
 
diff --git a/t/21_baseline_starttls.t b/t/21_baseline_starttls.t
index 17be1606d..ad50f90b5 100755
--- a/t/21_baseline_starttls.t
+++ b/t/21_baseline_starttls.t
@@ -26,6 +26,9 @@ my $openssl_out="";
 my $socket_regex_bl='(e|E)rror|\.\/testssl\.sh: line |(f|F)atal|(c|C)ommand not found';
 my $openssl_regex_bl='(e|E)rror|(f|F)atal|\.\/testssl\.sh: line |Oops|s_client connect problem|(c|C)ommand not found';
 
+# useful against "failed to flush stdout" messages
+STDOUT->autoflush(1);
+
 # my $socket_json="";
 # my $openssl_json="";
 # $check2run_smtp="--jsonfile tmp.json $check2run_smtp";
diff --git a/t/23_client_simulation.t b/t/23_client_simulation.t
index 555b8236e..ff2b34b91 100755
--- a/t/23_client_simulation.t
+++ b/t/23_client_simulation.t
@@ -21,6 +21,9 @@ my $openssl_out="";
 my $socket_regex_bl='(e|E)rror|\.\/testssl\.sh: line |(f|F)atal|(c|C)ommand not found';
 my $openssl_regex_bl='(e|E)rror|(f|F)atal|\.\/testssl\.sh: line |Oops|s_client connect problem|(c|C)ommand not found';
 
+# useful against "failed to flush stdout" messages
+STDOUT->autoflush(1);
+
 # my $socket_json="";
 # my $openssl_json="";
 # $check2run="--jsonfile tmp.json $check2run";