diff --git a/lib/Subtitle/SSA.pm b/lib/Subtitle/SSA.pm
index 0f52da6..e48c0db 100644
--- a/lib/Subtitle/SSA.pm
+++ b/lib/Subtitle/SSA.pm
@@ -44,11 +44,11 @@ sub parse {
     study $line;
 
     # check section switch
-    if ($line =~ m/^\s*\[(.+)\]\s*/o) {
-      my $name = $1;
+    if ($line =~ m/^\s*\[\s*([a-z0-9+ ]+)\s*\]\s*$/io) {
+      my $name = lc($1);
       if ($name =~ m{script \s+ info}oix) {
         $section = 'header';
-      } elsif ($name =~ m{events}oi) {
+      } elsif ($name eq 'events') {
         $section = 'events';
       } elsif ($name =~ m{v4(\+)? \s+ styles}oix) {
         $section = 'styles';
@@ -57,9 +57,10 @@ sub parse {
           $self->log(warn => "Set type to $self->{type} because of line $linenum (fallback mode)");
         }
       } else {
-        undef $section;
-        $self->log(debug => "Unknown section at line $linenum: $line");
+        $section = 'unknown';
+        $self->log(warn => "Unknown section at line $linenum: $line");
       }
+      $self->log(debug => "section changed to [$section] at line $linenum");
       next;
     }
     #