diff --git a/src/Printer.php b/src/Printer.php
index 5a1491c..e7a07eb 100644
--- a/src/Printer.php
+++ b/src/Printer.php
@@ -52,6 +52,7 @@ class Printer
                 $a = str_replace("\\", "\\\\", $a);
                 $a = str_replace("\n", "\\n", $a);
                 $a = str_replace("\r", "\\r", $a);
+                $a = str_replace("\t", "\\t", $a);
                 $a = str_replace("\"", "\\\"", $a);
                 return '"' . $a . '"';
             } else {
diff --git a/test/PrinterTest.php b/test/PrinterTest.php
new file mode 100644
index 0000000..2fcd06e
--- /dev/null
+++ b/test/PrinterTest.php
@@ -0,0 +1,89 @@
+<?php
+/**
+ * MadLisp language
+ * @link http://madlisp.com/
+ * @copyright Copyright (c) 2020 Pekka Laiho
+ */
+
+use PHPUnit\Framework\TestCase;
+
+use MadLisp\Func;
+use MadLisp\Hash;
+use MadLisp\MList;
+use MadLisp\Printer;
+use MadLisp\Symbol;
+use MadLisp\Vector;
+
+class PrinterTest extends TestCase
+{
+    public function notReadableProvider(): array
+    {
+        $mc = $this->createStub(Func::class);
+        $mc->method('isMacro')->willReturn(true);
+
+        $fn = $this->createStub(Func::class);
+        $fn->method('isMacro')->willReturn(false);
+
+        return [
+            [$mc, '<macro>'],
+            [$fn, '<function>'],
+            [new MList([new Symbol('aa'), new Symbol('bb'), new MList([new Symbol('cc')])]), '(aa bb (cc))'],
+            [new Vector([12, 34, new Vector([56])]), '[12 34 [56]]'],
+            [new Hash(['aa' => 'bb', 'cc' => new Hash(['dd' => 'ee'])]), '{aa:bb cc:{dd:ee}}'],
+            [new Symbol('abc'), 'abc'],
+            [new \stdClass(), '<object<stdClass>>'],
+            [true, 'true'],
+            [false, 'false'],
+            [null, 'null'],
+            [123, '123'],
+            [34.56, '34.56'],
+
+            // Test strings
+            ['abc', 'abc'],
+            ["a\\b\nc\rd\te\"f", "a\\b\nc\rd\te\"f"],
+        ];
+    }
+
+    /**
+     * @dataProvider notReadableProvider
+     */
+    public function testPrintNotReadable($input, string $expected)
+    {
+        $printer = new Printer();
+        $result = $printer->pstr($input, false);
+        $this->assertSame($expected, $result);
+    }
+
+    public function readableProvider(): array
+    {
+        return [
+            [new Hash(['aa' => 'bb', 'cc' => new Hash(['dd' => 'ee'])]), '{"aa":"bb" "cc":{"dd":"ee"}}'],
+            [new Symbol('abc'), 'abc'], // symbol is not quoted
+
+            // Test strings
+            ['abc', '"abc"'],
+            ["a\\b\nc\rd\te\"f", "\"a\\\\b\\nc\\rd\\te\\\"f\""],
+        ];
+    }
+
+    /**
+     * @dataProvider readableProvider
+     */
+    public function testPrintReadable($input, string $expected)
+    {
+        $printer = new Printer();
+        $result = $printer->pstr($input, true);
+        $this->assertSame($expected, $result);
+    }
+
+    public function testPrintResource()
+    {
+        $file = tmpfile();
+
+        $printer = new Printer();
+        $result = $printer->pstr($file, false);
+        $this->assertSame('<resource>', $result);
+
+        fclose($file);
+    }
+}
diff --git a/test/ReaderTest.php b/test/ReaderTest.php
index 87ea337..c62ddfc 100644
--- a/test/ReaderTest.php
+++ b/test/ReaderTest.php
@@ -7,7 +7,6 @@
 
 use PHPUnit\Framework\TestCase;
 
-use MadLisp\MadLispException;
 use MadLisp\Hash;
 use MadLisp\MList;
 use MadLisp\Reader;