diff --git a/core/lib/Foswiki/Query/OP_lc.pm b/core/lib/Foswiki/Query/OP_lc.pm
index 8ee8b52d92..c69929dc6d 100644
--- a/core/lib/Foswiki/Query/OP_lc.pm
+++ b/core/lib/Foswiki/Query/OP_lc.pm
@@ -27,7 +27,8 @@ sub new {
 sub evaluate {
     my $this = shift;
     my $node = shift;
-    return $this->evalUnary( $node, sub { lc(shift) }, @_ );
+    return $this->evalUnary( $node,
+        sub { my $arg = shift; defined $arg ? lc($arg) : undef }, @_ );
 }
 
 1;
@@ -36,7 +37,7 @@ Author: Crawford Currie http://c-dot.co.uk
 
 Foswiki - The Free and Open Source Wiki, http://foswiki.org/
 
-Copyright (C) 2008-2010 Foswiki Contributors. Foswiki Contributors
+Copyright (C) 2008-2011 Foswiki Contributors. Foswiki Contributors
 are listed in the AUTHORS file in the root of this distribution.
 NOTE: Please extend that file, not this notice.
 
diff --git a/core/lib/Foswiki/Query/OP_uc.pm b/core/lib/Foswiki/Query/OP_uc.pm
index fd4d7bf30d..5f52d5431c 100644
--- a/core/lib/Foswiki/Query/OP_uc.pm
+++ b/core/lib/Foswiki/Query/OP_uc.pm
@@ -27,7 +27,8 @@ sub new {
 sub evaluate {
     my $this = shift;
     my $node = shift;
-    return $this->evalUnary( $node, sub { uc(shift) }, @_ );
+    return $this->evalUnary( $node,
+        sub { my $arg = shift; defined $arg ? uc($arg) : undef }, @_ );
 }
 
 1;
@@ -36,7 +37,7 @@ Author: Crawford Currie http://c-dot.co.uk
 
 Foswiki - The Free and Open Source Wiki, http://foswiki.org/
 
-Copyright (C) 2008-2010 Foswiki Contributors. Foswiki Contributors
+Copyright (C) 2008-2011 Foswiki Contributors. Foswiki Contributors
 are listed in the AUTHORS file in the root of this distribution.
 NOTE: Please extend that file, not this notice.