diff --git a/opac/opac-ISBDdetail.pl b/opac/opac-ISBDdetail.pl
index d60f8fcb26..4706fde55f 100755
--- a/opac/opac-ISBDdetail.pl
+++ b/opac/opac-ISBDdetail.pl
@@ -42,6 +42,8 @@ the items attached to the biblio
 =cut
 
 use strict;
+use warnings;
+
 use C4::Auth;
 use C4::Context;
 use C4::Output;
diff --git a/opac/opac-modrequest.pl b/opac/opac-modrequest.pl
index 01b45f1460..bada04da94 100755
--- a/opac/opac-modrequest.pl
+++ b/opac/opac-modrequest.pl
@@ -23,6 +23,8 @@
 # Suite 330, Boston, MA  02111-1307 USA
 
 use strict;
+use warnings;
+
 use CGI;
 use C4::Output;
 use C4::Reserves;
diff --git a/opac/opac-tags_subject.pl b/opac/opac-tags_subject.pl
index 84e8fc3bdc..5836f704d5 100755
--- a/opac/opac-tags_subject.pl
+++ b/opac/opac-tags_subject.pl
@@ -25,6 +25,8 @@ TODO :: Description here
 =cut
 
 use strict;
+use warnings;
+
 use C4::Auth;
 use C4::Context;
 use C4::Output;