diff --git a/t/02_clientsim_txt_parsable.t b/t/02_clientsim_txt_parsable.t
index 6885ef8..b58210d 100755
--- a/t/02_clientsim_txt_parsable.t
+++ b/t/02_clientsim_txt_parsable.t
@@ -4,6 +4,7 @@
 # doesn't have any syntax errors
 
 use strict;
+use warnings;
 use Test::More;
 
 my $tests = 0;
diff --git a/t/03_syntax_check.t b/t/03_syntax_check.t
index cf27689..586f47c 100755
--- a/t/03_syntax_check.t
+++ b/t/03_syntax_check.t
@@ -3,6 +3,7 @@
 # Basics: are there semantic errors which are easy to spot?
 
 use strict;
+use warnings;
 use Test::More;
 
 my $tests = 0;
diff --git a/t/12_diff_opensslversions.t b/t/12_diff_opensslversions.t
index 8464133..5586847 100755
--- a/t/12_diff_opensslversions.t
+++ b/t/12_diff_opensslversions.t
@@ -5,6 +5,7 @@
 # This runs a basic test with the supplied openssl vs /usr/bin/openssl
 
 use strict;
+use warnings;
 use Test::More;
 use Data::Dumper;
 use Text::Diff;
diff --git a/t/32_isHTML_valid.t b/t/32_isHTML_valid.t
index 853cc1d..de78aca 100755
--- a/t/32_isHTML_valid.t
+++ b/t/32_isHTML_valid.t
@@ -4,6 +4,7 @@
 # This could be amended by using HTML::Tidy or HTML::Valid
 
 use strict;
+use warnings;
 use Test::More;
 use Data::Dumper;
 use Text::Diff;
diff --git a/t/52_ocsp_revoked.t b/t/52_ocsp_revoked.t
index 6b8e186..3d79864 100755
--- a/t/52_ocsp_revoked.t
+++ b/t/52_ocsp_revoked.t
@@ -7,6 +7,7 @@
 # We don't use a full run, only the certificate section.
 
 use strict;
+use warnings;
 use Test::More;
 use Data::Dumper;
 use Text::Diff;
diff --git a/t/53_hsts_preload.t b/t/53_hsts_preload.t
index 66a5552..9a63357 100755
--- a/t/53_hsts_preload.t
+++ b/t/53_hsts_preload.t
@@ -6,6 +6,7 @@
 # We don't use a full run, only the HTTP header section.
 
 use strict;
+use warnings;
 use Test::More;
 
 my $tests = 0;
diff --git a/t/61_diff_testsslsh.t b/t/61_diff_testsslsh.t
index 5e813eb..41421d2 100755
--- a/t/61_diff_testsslsh.t
+++ b/t/61_diff_testsslsh.t
@@ -9,6 +9,7 @@
 #
 
 use strict;
+use warnings;
 use Test::More;
 use Data::Dumper;
 use Text::Diff;