diff --git a/src/Shaper/Arabic.php b/src/Shaper/Arabic.php
index f2264e9d9..706b10a62 100644
--- a/src/Shaper/Arabic.php
+++ b/src/Shaper/Arabic.php
@@ -174,27 +174,14 @@ public static function shape(&$info, $arabGlyphs, $glyphClassMarks, $usetags, $s
 			$chars[] = $info[$i]['hex'];
 		}
 
-		$crntChar = null;
-		$prevChar = null;
 		$nextChar = null;
 		$output = [];
 		$max = count($chars);
 		for ($i = $max - 1; $i >= 0; $i--) {
 			$crntChar = $chars[$i];
-			if ($i > 0) {
-				$prevChar = hexdec($chars[$i - 1]);
-			} else {
-				$prevChar = null;
-			}
-			if ($prevChar && isset($transparentJoin[$prevChar]) && isset($chars[$i - 2])) {
-				$prevChar = hexdec($chars[$i - 2]);
-				if ($prevChar && isset($transparentJoin[$prevChar]) && isset($chars[$i - 3])) {
-					$prevChar = hexdec($chars[$i - 3]);
-					if ($prevChar && isset($transparentJoin[$prevChar]) && isset($chars[$i - 4])) {
-						$prevChar = hexdec($chars[$i - 4]);
-					}
-				}
-			}
+			// joining sees the base a mark is written on, however many marks the base carries
+			$n = self::skipTransparent($chars, $i, -1, $transparentJoin);
+			$prevChar = isset($chars[$n]) ? hexdec($chars[$n]) : null;
 			if ($crntChar && isset($transparentJoin[hexdec($crntChar)])) {
 				// If next_char = RightJoining && prev_char = LeftJoining:
 				if (isset($chars[$i + 1]) && $chars[$i + 1] && isset(self::$rightJoining[hexdec($chars[$i + 1])]) && $prevChar && isset(self::$leftJoining[$prevChar])) {
diff --git a/tests/Mpdf/Shaper/ArabicTest.php b/tests/Mpdf/Shaper/ArabicTest.php
index b64f38d54..b8f0f1ac3 100644
--- a/tests/Mpdf/Shaper/ArabicTest.php
+++ b/tests/Mpdf/Shaper/ArabicTest.php
@@ -35,6 +35,9 @@ class ArabicTest extends \Yoast\PHPUnitPolyfills\TestCases\TestCase
 	/** U+073A SYRIAC HBASA ABOVE */
 	const HBASA = '0073A';
 
+	/** U+073B SYRIAC HBASA BELOW */
+	const HBASA_BELOW = '0073B';
+
 	/** U+0712 SYRIAC LETTER BETH, dual-joining */
 	const BETH = '00712';
 
@@ -117,6 +120,40 @@ public function testAMarkBetweenTwoLettersDoesNotBreakTheirJoin()
 		$this->assertSame([['B_INIT', 2], [self::FATHA, 0], ['B_FINA', 1]], $forms);
 	}
 
+	/**
+	 * Nothing limits how many marks a base carries, and the lookback stepped over at most three of
+	 * them: a fourth left the following letter reading a mark as the character behind it, and a mark
+	 * joins nothing. GravityPDF/mpdf#154.
+	 *
+	 * The first letter is asserted alongside the last because the two directions are found
+	 * differently - forwards is the last letter the backwards walk over the run passed, which never
+	 * had a limit - and it is the pair that says the marks are invisible to joining from either side.
+	 */
+	public function testALetterJoinsToTheBaseBeforeItHoweverManyMarksAreBetweenThem()
+	{
+		$four = [self::BETH, self::PTHAHA, self::ZQAPHA, self::RBASA, self::HBASA, self::BETH];
+		$five = [self::BETH, self::PTHAHA, self::ZQAPHA, self::RBASA, self::HBASA, self::HBASA_BELOW, self::BETH];
+
+		$forms = $this->shape($four, self::ALL_FORMS, 'syrc');
+
+		$this->assertSame(['BE_INIT', 2], $forms[0]);
+		$this->assertSame(['BE_FINA', 1], $forms[5]);
+		$this->assertSame(['BE_FINA', 1], $this->shape($five, self::ALL_FORMS, 'syrc')[6]);
+	}
+
+	/**
+	 * The marks counted are the Transparent-Joining table together with GDEF's mark class, so a mark
+	 * only the font declares takes up a place in the walk like any other.
+	 */
+	public function testAMarkOnlyGdefDeclaresIsSteppedOverWithTheRest()
+	{
+		$run = [self::BETH, self::PTHAHA, self::ZQAPHA, self::RBASA, self::COMBINING_GRAVE, self::BETH];
+
+		$forms = $this->shape($run, self::ALL_FORMS, 'syrc', self::COMBINING_GRAVE);
+
+		$this->assertSame(['BE_FINA', 1], $forms[5]);
+	}
+
 	/**
 	 * The four form features can be switched off through OTLtags, in which case the character is left
 	 * as it came in rather than substituted
@@ -300,6 +337,21 @@ public function testAPointedWordDrawsTheSameAlaphAsTheUnpointedWord()
 		}
 	}
 
+	/**
+	 * Through a real font: the marks are drawn where they were written and the letters either side
+	 * read as though they were not there, so a heavily pointed word has to draw the same two BETHs as
+	 * the unpointed one. Estrangelo Edessa states no isolated BETH either, so the second letter losing
+	 * its final form left the nominal U+0712 behind.
+	 */
+	public function testAHeavilyPointedWordDrawsTheSameLettersAsTheUnpointedWord()
+	{
+		$unpointed = $this->render([self::BETH, self::BETH]);
+		$pointed = $this->render([self::BETH, self::PTHAHA, self::ZQAPHA, self::RBASA, self::HBASA, self::BETH]);
+
+		$this->assertSame($unpointed[0], $pointed[0]);
+		$this->assertSame($unpointed[1], $pointed[5]);
+	}
+
 	/**
 	 * The same character through a real font, which is where the wrong entry showed: Estrangelo Edessa
 	 * carries a BETH for each of the four forms, and the form the shaper asks for is the glyph that