diff --git a/bibcop.pl b/bibcop.pl
index 791a518..523b1de 100755
--- a/bibcop.pl
+++ b/bibcop.pl
@@ -355,8 +355,14 @@ sub check_year {
   my (%entry) = @_;
   if (exists $entry{'year'}) {
     my $year = $entry{'year'};
-    if (not $year =~ /^[0-9]{3,4}$/) {
-      return "The format of the 'year' is wrong"
+    if ($year =~ /^\{.+\}$/) {
+      return;
+    }
+    if (not $year =~ /^[0-9]+$/) {
+      return "The format of the 'year' is wrong, may only contain numbers or must be wrapped in curly braces"
+    }
+    if (not $year =~ /^[0-9]{4}$/) {
+      return "Exactly four digits must be present in the 'year', or it must be wrapped in curly braces"
     }
   }
 }
diff --git a/perl-tests/checks.pl b/perl-tests/checks.pl
index 7ca44fe..cdcd076 100644
--- a/perl-tests/checks.pl
+++ b/perl-tests/checks.pl
@@ -95,6 +95,14 @@ package bibcop;
 check_passes($f, ('title' => 'Data Flow Languages and Architecture'));
 check_passes($f, ('title' => 'A Preliminary Architecture for a Basic Data-Flow Processor'));
 
+$f = 'check_year';
+check_fails($f, ('year' => 'hello'));
+check_fails($f, ('year' => '20019'));
+check_fails($f, ('year' => '2009-2011'));
+check_passes($f, ('year' => '{400 BC}'));
+check_passes($f, ('year' => '2022'));
+check_passes($f, ('year' => '1612'));
+
 $f = 'check_pages';
 check_fails($f, ('pages' => '1a'));
 check_fails($f, ('pages' => '40A'));