diff --git a/src/Spies/AnyValue.php b/src/Spies/AnyValue.php
index 0855822..5f8d279 100644
--- a/src/Spies/AnyValue.php
+++ b/src/Spies/AnyValue.php
@@ -3,4 +3,8 @@
 
 class AnyValue {
 	public $value = 'ANYTHING';
+
+	public function __toString() {
+		return 'AnyValue';
+	}
 }
diff --git a/src/Spies/ArgumentFormatter.php b/src/Spies/ArgumentFormatter.php
index 591b093..f40ca36 100644
--- a/src/Spies/ArgumentFormatter.php
+++ b/src/Spies/ArgumentFormatter.php
@@ -16,6 +16,12 @@ public function __toString() {
 	}
 
 	private function get_args_as_array() {
-		return implode( ', ', array_map( 'json_encode', $this->args ) );
+		$stringify_argument = function ( $argument ) {
+			if ( method_exists( $argument, '__toString' ) ) {
+				return $argument->__toString();
+			}
+			return json_encode( $argument );
+		};
+		return implode( ', ', array_map( $stringify_argument, $this->args ) );
 	}
 }
diff --git a/src/Spies/MatchArray.php b/src/Spies/MatchArray.php
index 188e14e..c106d89 100644
--- a/src/Spies/MatchArray.php
+++ b/src/Spies/MatchArray.php
@@ -34,5 +34,9 @@ private function is_associative( $arr ) {
 		}
 		return array_keys( $arr ) !== range( 0, count( $arr ) - 1 );
 	}
+
+	public function __toString() {
+		return 'MatchArray(' . json_encode( $this->expected_array ) . ')';
+	}
 }
 
diff --git a/src/Spies/MatchPattern.php b/src/Spies/MatchPattern.php
index ef8bd80..b1423c6 100644
--- a/src/Spies/MatchPattern.php
+++ b/src/Spies/MatchPattern.php
@@ -16,6 +16,8 @@ public function is_match( $actual ) {
 		}
 		return false;
 	}
-}
-
 
+	public function __toString() {
+		return "MatchPattern('{$this->expected_pattern}')";
+	}
+}
diff --git a/tests/ExpectationTest.php b/tests/ExpectationTest.php
index f28987c..0212a36 100644
--- a/tests/ExpectationTest.php
+++ b/tests/ExpectationTest.php
@@ -286,6 +286,13 @@ public function test__with__and__match_pattern__is_not_met_if_the_spy_is_called_
 		$this->assertFalse( $expectation->met_expectations() );
 	}
 
+	public function test__match_pattern__reports_fail_message_on_fail() {
+		$spy = \Spies\make_spy();
+		$expectation = \Spies\expect_spy( $spy )->to_have_been_called->with( 'foo', \Spies\match_pattern( '/Bart/i' ) );
+		$spy( 'foo', 'slartiblargfast' );
+		$this->assertContains( 'Failed asserting that a spy is called with arguments: ( "foo", MatchPattern(\'/Bart/i\') )', $expectation->get_fail_message() );
+	}
+
 	public function test__with__and__match_array__is_met_if_the_spy_is_called_with_matching_key_values() {
 		$spy = \Spies\make_spy();
 		$expectation = \Spies\expect_spy( $spy )->to_have_been_called->with( 'foo', \Spies\match_array( [ 'foo' => 'bar', 'flim' => 'flam' ] ) );
@@ -335,6 +342,13 @@ public function test__with__and__match_array__is_not_met_if_the_spy_is_called_wi
 		$this->assertFalse( $expectation->met_expectations() );
 	}
 
+	public function test__match_array__reports_fail_message_on_fail() {
+		$spy = \Spies\make_spy();
+		$expectation = \Spies\expect_spy( $spy )->to_have_been_called->with( 'foo', \Spies\match_array( [ 'flim' => 'flam' ] ) );
+		$spy( 'foo', [ 'bar' => 'baz', 'foo' => 'bar' ] );
+		$this->assertContains( 'Failed asserting that a spy is called with arguments: ( "foo", MatchArray({"flim":"flam"}) )', $expectation->get_fail_message() );
+	}
+
 	public function test__with__and__any__is_met_if_the_spy_is_called_with_any_arguments() {
 		$spy = \Spies\make_spy();
 		$expectation = \Spies\expect_spy( $spy )->to_have_been_called->with( 'foo', \Spies\any() );
@@ -342,6 +356,13 @@ public function test__with__and__any__is_met_if_the_spy_is_called_with_any_argum
 		$this->assertTrue( $expectation->met_expectations() );
 	}
 
+	public function test__any__reports_fail_message_on_fail() {
+		$spy = \Spies\make_spy();
+		$expectation = \Spies\expect_spy( $spy )->to_have_been_called->with( 'foo', \Spies\any() );
+		$spy( 'bar' );
+		$this->assertContains( 'Failed asserting that a spy is called with arguments: ( "foo", AnyValue )', $expectation->get_fail_message() );
+	}
+
 	public function test__with__is_not_met_if_the_spy_is_called_with_no_arguments() {
 		$spy = \Spies\make_spy();
 		$expectation = \Spies\expect_spy( $spy )->to_have_been_called->with( 'foo', 'bar' );