diff --git a/src/Components/Blocks/BlockQuote.php b/src/Components/Blocks/BlockQuote.php
index d1853a7..8b596c7 100644
--- a/src/Components/Blocks/BlockQuote.php
+++ b/src/Components/Blocks/BlockQuote.php
@@ -67,7 +67,10 @@ final class BlockQuote implements ContinuableBlock
             return null;
         }
 
-        if ($Context->line()->text()[0] === '>' && \preg_match('/^(>[ \t]?+)(.*+)/', $Context->line()->text(), $matches)) {
+        if (
+            \substr($Context->line()->text(), 0, 1) === '>'
+            && \preg_match('/^(>[ \t]?+)(.*+)/', $Context->line()->text(), $matches)
+        ) {
             $indentOffset = $Context->line()->indentOffset() + $Context->line()->indent() + \strlen($matches[1]);
 
             $recoveredSpaces = 0;
diff --git a/src/Components/Blocks/FencedCode.php b/src/Components/Blocks/FencedCode.php
index 24bad21..85b1117 100644
--- a/src/Components/Blocks/FencedCode.php
+++ b/src/Components/Blocks/FencedCode.php
@@ -56,7 +56,7 @@ final class FencedCode implements ContinuableBlock
         Block $Block = null,
         State $State = null
     ) {
-        $marker = $Context->line()->text()[0];
+        $marker = \substr($Context->line()->text(), 0, 1);
 
         $openerLength = \strspn($Context->line()->text(), $marker);
 
diff --git a/src/Components/Blocks/Header.php b/src/Components/Blocks/Header.php
index 615937d..d9dfb86 100644
--- a/src/Components/Blocks/Header.php
+++ b/src/Components/Blocks/Header.php
@@ -58,9 +58,11 @@ final class Header implements Block
 
         $text = \ltrim($Context->line()->text(), '#');
 
+        $firstChar = \substr($text, 0, 1);
+
         if (
-            $State->get(StrictMode::class)->isEnabled() && isset($text[0])
-            && $text[0] !== ' ' && $text[0] !== "\t"
+            $State->get(StrictMode::class)->isEnabled()
+            && \trim($firstChar, " \t") !== ''
         ) {
             return null;
         }
diff --git a/src/Components/Blocks/Rule.php b/src/Components/Blocks/Rule.php
index ceb7b6a..1622ff0 100644
--- a/src/Components/Blocks/Rule.php
+++ b/src/Components/Blocks/Rule.php
@@ -27,7 +27,7 @@ final class Rule implements Block
             return null;
         }
 
-        $marker = $Context->line()->text()[0];
+        $marker = \substr($Context->line()->text(), 0, 1);
 
         if (
             \substr_count($Context->line()->text(), $marker) >= 3
diff --git a/src/Components/Blocks/SetextHeader.php b/src/Components/Blocks/SetextHeader.php
index e636778..b684dec 100644
--- a/src/Components/Blocks/SetextHeader.php
+++ b/src/Components/Blocks/SetextHeader.php
@@ -46,8 +46,17 @@ final class SetextHeader implements Block
             return null;
         }
 
-        if ($Context->line()->indent() < 4 && \chop(\chop($Context->line()->text(), " \t"), $Context->line()->text()[0]) === '') {
-            $level = $Context->line()->text()[0] === '=' ? 1 : 2;
+        $marker = \substr($Context->line()->text(), 0, 1);
+
+        if ($marker !== '=' && $marker !== '-') {
+            return null;
+        }
+
+        if (
+            $Context->line()->indent() < 4
+            && \chop(\chop($Context->line()->text(), " \t"), $marker) === ''
+        ) {
+            $level = ($marker === '=' ? 1 : 2);
 
             return new self(\trim($Block->text()), $level);
         }
diff --git a/src/Components/Blocks/TList.php b/src/Components/Blocks/TList.php
index d9dd683..94405f4 100644
--- a/src/Components/Blocks/TList.php
+++ b/src/Components/Blocks/TList.php
@@ -89,7 +89,7 @@ final class TList implements ContinuableBlock
         State $State = null
     ) {
         list($type, $pattern) = (
-            $Context->line()->text()[0] <= '-'
+            \substr($Context->line()->text(), 0, 1) <= '-'
             ? ['ul', '[*+-]']
             : ['ol', '[0-9]{1,9}+[.\)]']
         );
diff --git a/src/Components/Blocks/Table.php b/src/Components/Blocks/Table.php
index 7e3f03c..76c9b1a 100644
--- a/src/Components/Blocks/Table.php
+++ b/src/Components/Blocks/Table.php
@@ -101,7 +101,11 @@ final class Table implements ContinuableBlock
             return null;
         }
 
-        if (\count($this->alignments) !== 1 && $Context->line()->text()[0] !== '|' && !\strpos($Context->line()->text(), '|')) {
+        if (
+            \count($this->alignments) !== 1
+            && \substr($Context->line()->text(), 0, 1) !== '|'
+            && !\strpos($Context->line()->text(), '|')
+        ) {
             return null;
         }
 
@@ -148,7 +152,7 @@ final class Table implements ContinuableBlock
             /** @var _Alignment|null */
             $alignment = null;
 
-            if ($dividerCell[0] === ':') {
+            if (\substr($dividerCell, 0, 1) === ':') {
                 $alignment = 'left';
             }
 
diff --git a/src/Components/Inlines/Code.php b/src/Components/Inlines/Code.php
index 5e51b90..85e20f2 100644
--- a/src/Components/Inlines/Code.php
+++ b/src/Components/Inlines/Code.php
@@ -33,7 +33,7 @@ final class Code implements Inline
      */
     public static function build(Excerpt $Excerpt, State $State)
     {
-        $marker = $Excerpt->text()[0];
+        $marker = \substr($Excerpt->text(), 0, 1);
 
         if ($marker !== '`') {
             return null;
diff --git a/src/Components/Inlines/Emphasis.php b/src/Components/Inlines/Emphasis.php
index 6203060..38498ca 100644
--- a/src/Components/Inlines/Emphasis.php
+++ b/src/Components/Inlines/Emphasis.php
@@ -52,17 +52,20 @@ final class Emphasis implements Inline
      */
     public static function build(Excerpt $Excerpt, State $State)
     {
-        if (! isset($Excerpt->text()[1])) {
+        if (\strlen($Excerpt->text()) < 3) {
             return null;
         }
 
-        $marker = $Excerpt->text()[0];
+        $marker = \substr($Excerpt->text(), 0, 1);
 
         if ($marker !== '*' && $marker !== '_') {
             return null;
         }
 
-        if ($Excerpt->text()[1] === $marker && \preg_match(self::$STRONG_REGEX[$marker], $Excerpt->text(), $matches)) {
+        if (
+            \substr($Excerpt->text(), 1, 1) === $marker
+            && \preg_match(self::$STRONG_REGEX[$marker], $Excerpt->text(), $matches)
+        ) {
             $emphasis = 'strong';
         } elseif (\preg_match(self::$EM_REGEX[$marker], $Excerpt->text(), $matches)) {
             $emphasis = 'em';
diff --git a/src/Components/Inlines/EscapeSequence.php b/src/Components/Inlines/EscapeSequence.php
index 75ae4b8..369b71c 100644
--- a/src/Components/Inlines/EscapeSequence.php
+++ b/src/Components/Inlines/EscapeSequence.php
@@ -33,8 +33,10 @@ final class EscapeSequence implements Inline
      */
     public static function build(Excerpt $Excerpt, State $State)
     {
-        if (isset($Excerpt->text()[1]) && \strpbrk($c = $Excerpt->text()[1], self::SPECIALS) !== false) {
-            return new self($c);
+        $char = \substr($Excerpt->text(), 1, 1);
+
+        if ($char !== '' && \strpbrk($char, self::SPECIALS) !== false) {
+            return new self($char);
         }
 
         return null;
diff --git a/src/Components/Inlines/Strikethrough.php b/src/Components/Inlines/Strikethrough.php
index e41af82..33177fb 100644
--- a/src/Components/Inlines/Strikethrough.php
+++ b/src/Components/Inlines/Strikethrough.php
@@ -41,7 +41,7 @@ final class Strikethrough implements Inline
             return null;
         }
 
-        if ($text[1] === '~' && \preg_match('/^~~(?=\S)(.+?)(?<=\S)~~/', $text, $matches)) {
+        if (\substr($text, 1, 1) === '~' && \preg_match('/^~~(?=\S)(.+?)(?<=\S)~~/', $text, $matches)) {
             return new self($matches[1], \strlen($matches[0]));
         }
 
diff --git a/src/Parsedown.php b/src/Parsedown.php
index 3e28913..2958fe6 100644
--- a/src/Parsedown.php
+++ b/src/Parsedown.php
@@ -98,7 +98,7 @@ final class Parsedown
                 }
             }
 
-            $marker = $Line->text()[0];
+            $marker = \substr($Line->text(), 0, 1);
 
             $potentialBlockTypes = \array_merge(
                 $State->get(BlockTypes::class)->unmarked(),