diff --git a/sax/xml/pct/actions.pm b/sax/xml/pct/actions.pm
index 1f53d6c..161ab12 100644
--- a/sax/xml/pct/actions.pm
+++ b/sax/xml/pct/actions.pm
@@ -121,6 +121,10 @@ method STag($/) {
     our $elt_stack;
     $elt_stack.push( $<Name> );
     for ( $<Attribute> ) {
+        if ( %attr{ $_<Name> } ) {
+            fire( 'error',
+                  :Exception( "duplicate attribute: " ~ $_<Name> ) );
+        }
         %attr{ $_<Name> } := normalize( $_<AttValue>[0] );
     }
     fire( 'start_element',
@@ -140,7 +144,7 @@ method ETag($/) {
     }
     else {
         fire( 'error',
-              :Exception( "unbalanced end tag: " ~ $<Name> ~ " (" ~ $curr ~ " expected)") );
+              :Exception( "unbalanced end tag: " ~ $<Name> ~ " (" ~ $curr ~ " expected)" ) );
     }
     make PCT::Node.new();
 }
@@ -149,6 +153,10 @@ method ETag($/) {
 method EmptyElemTag($/) {
     my %attr;
     for ( $<Attribute> ) {
+        if ( %attr{ $_<Name> } ) {
+            fire( 'error',
+                  :Exception( "duplicate attribute: " ~ $_<Name> ) );
+        }
         %attr{ $_<Name> } := normalize( $_<AttValue>[0] );
     }
     fire( 'start_element',
diff --git a/t/20-element.t b/t/20-element.t
index 1cad329..cf4f19f 100644
--- a/t/20-element.t
+++ b/t/20-element.t
@@ -14,7 +14,7 @@ use warnings;
 use FindBin;
 use lib "$FindBin::Bin/../../../lib", "$FindBin::Bin";
 
-use Parrot::Test tests => 5;
+use Parrot::Test tests => 7;
 use Test::More;
 
 language_output_is( 'xml', <<'CODE', <<'OUT', 'start/end' );
@@ -29,6 +29,12 @@ CODE
 <elt a="1" b="txt">content</elt>
 OUT
 
+language_output_like( 'xml', <<'CODE', <<'OUT', 'start/end with duplicated attributes' );
+<elt a="1" a='txt' >content</elt  >
+CODE
+/^duplicate attribute: a\n/
+OUT
+
 language_output_is( 'xml', <<'CODE', <<'OUT', 'empty' );
 <elt  />
 CODE
@@ -41,6 +47,12 @@ CODE
 <elt a="1"></elt>
 OUT
 
+language_output_like( 'xml', <<'CODE', <<'OUT', 'empty with duplicated attributes' );
+<elt a='1' a='2'/>
+CODE
+/^duplicate attribute: a\n/
+OUT
+
 language_output_like( 'xml', <<'CODE', <<'OUT', 'unbalanced start/end' );
 <a><b>content</c></a>
 CODE