diff --git a/lib/Math/Giac.pm b/lib/Math/Giac.pm
index 7caf7bc..3f3c22d 100644
--- a/lib/Math/Giac.pm
+++ b/lib/Math/Giac.pm
@@ -7,7 +7,7 @@ use File::Temp;
 
 =head1 NAME
 
-Math::Giac - The great new Math::Giac!
+Math::Giac - A perl interface to giac.
 
 =head1 VERSION
 
@@ -36,6 +36,9 @@ our $VERSION = '0.0.1';
     $results=$giac->run('mathml(sin(x)+cos(pi)-3)');
     print $results."\n";
 
+    $giac->set_vars({ A=>2 });
+    my $results=$giac->run('sin(A)+cos(pi)-3');
+
 =head1 METHODS
 
 =head2 new
@@ -103,7 +106,7 @@ sub run {
 	my @var_list   = keys( %{ $self->{vars} } );
 	my $vars_addon = '';
 	foreach my $cur_var (@var_list) {
-		my $vars_addon = $vars_addon . $cur_var . ':=' . $$self->{vars}{$cur_var} . "\n";
+		$vars_addon = $vars_addon . $cur_var . ':=' . $self->{vars}{$cur_var} . "\n";
 	}
 
 	$to_run = $vars_addon . $to_run;
diff --git a/t/giac.t b/t/giac.t
index e3adff6..0a84c5d 100644
--- a/t/giac.t
+++ b/t/giac.t
@@ -13,7 +13,7 @@ BEGIN {
 my $the_bin = `/bin/sh -c 'which giac 2> /dev/null'`;
 if ( $? eq 0 ){
 
-	$extra_tests=3;
+	$extra_tests=7;
 
 	my $worked=0;
 	my $giac;
@@ -21,7 +21,7 @@ if ( $? eq 0 ){
 		$giac=Math::Giac->new;
 		$worked=1;
 	};
-	ok( $worked eq '1', 'init check') or diag('failed to init the module');
+	ok( $worked eq '1', 'init check') or diag('failed to init the module... '.$@);
 
 	# basic single line return test
 	my $returned='';
@@ -44,6 +44,45 @@ if ( $? eq 0 ){
 		$extra_error='... '.$@;
 	}
 	ok( $returned =~ /MathML/, 'run check') or diag('"mathml(sin(pi))" returned "'.$returned.'" and does not match /MathML/'.$extra_error);
+
+	# make sure that we can set the variables
+	$worked=1;
+	eval{
+		$giac->vars_set({A=>2});
+		$worked=1;
+	};
+	ok( $worked eq '1', 'vars_set') or diag('Calling vars_set failed... '.$@);
+
+	# run a test using a variable
+	$returned='';
+	$extra_error='';
+	eval{
+		$returned=$giac->run("3+A");
+	};
+	if ( $@ ){
+		$extra_error='... '.$@;
+	}
+	ok( $returned eq '5', 'variable test') or diag('"3+A" where A=2 returned "'.$returned.'" instead of "5"'.$extra_error);
+
+	# make sure that we can clear
+	$worked=1;
+	eval{
+		$giac->vars_clear;
+		$worked=1;
+	};
+	ok( $worked eq '1', 'vars_clear') or diag('Calling vars_clear failed... '.$@);
+
+	# run a test using a variable post clearing the vars
+	$returned='';
+	$extra_error='';
+	eval{
+		$returned=$giac->run("3+A");
+	};
+	if ( $@ ){
+		$extra_error='... '.$@;
+	}
+	ok( $returned eq '3+A', 'variable test 2') or diag('"3+A" where A=undef returned "'.$returned.'" instead of "3+A"'.$extra_error);
+
 }
 
 my $tests_ran=1+$extra_tests;