diff --git a/samples/bugs/Issue391.pdf b/samples/bugs/Issue391.pdf
new file mode 100644
index 00000000..3294f13a
Binary files /dev/null and b/samples/bugs/Issue391.pdf differ
diff --git a/src/Smalot/PdfParser/Font.php b/src/Smalot/PdfParser/Font.php
index 0be46d78..deb2d6ce 100644
--- a/src/Smalot/PdfParser/Font.php
+++ b/src/Smalot/PdfParser/Font.php
@@ -106,6 +106,7 @@ public function translateChar($char, $use_default = true)
         if (
             \strlen($char) < 2
             && $this->has('Encoding')
+            && $this->get('Encoding') instanceof Encoding
             && WinAnsiEncoding::class === $this->get('Encoding')->__toString()
         ) {
             $fallbackDecoded = self::uchr($dec);
diff --git a/tests/Integration/ParserTest.php b/tests/Integration/ParserTest.php
index 4b217219..dee42d27 100644
--- a/tests/Integration/ParserTest.php
+++ b/tests/Integration/ParserTest.php
@@ -238,6 +238,31 @@ public function testIssue359()
         // $this->assertStringContainsString('sprawie swobodnego przepływu takich danych oraz uchylenia dyrektywy', $document->getText());
     }
 
+    /**
+     * Tests if PDF triggers "Call to undefined method Smalot\PdfParser\Header::__toString()".
+     *
+     * It happened because there was a check missing in Font.php (~ line 109).
+     *
+     * @see https://github.com/smalot/pdfparser/issues/391
+     */
+    public function testIssue391()
+    {
+        /**
+         * PDF provided by @dhildreth for usage in our test environment.
+         *
+         * @see https://github.com/smalot/pdfparser/issues/391#issuecomment-783504599
+         */
+        $filename = $this->rootDir.'/samples/bugs/Issue391.pdf';
+
+        $document = $this->fixture->parseFile($filename);
+
+        // check for an example string (PDF consists of many pages)
+        $this->assertStringContainsString(
+            '(This Code will be changed while mass production)',
+            $document->getText()
+        );
+    }
+
     /**
      * Tests behavior when changing default font space limit (-50).
      *