diff --git a/lib/Encoding/ISO2022JP.php b/lib/Encoding/ISO2022JP.php
index ad38a74..793c455 100644
--- a/lib/Encoding/ISO2022JP.php
+++ b/lib/Encoding/ISO2022JP.php
@@ -185,28 +185,48 @@ class ISO2022JP extends AbstractEncoding implements ModalCoder, Decoder {
     }
 
     public function asciiSpan(string $mask, int $length = null): string {
-        if ($this->mode === self::ASCII_STATE) {
-            $exc = '/[\x0E\x0F\x1B\x80-\xFF]/s';
-        } elseif ($this->mode === self::ROMAN_STATE) {
-            $exc = '/[\x0E\x0F\x1B\x5C\x7E\x80-\xFF]/s';
-        } else {
-            // in other modes ASCII characters are never returned
-            return "";
-        }
-        $mask = preg_replace($exc, "", $mask);
-        if ($length !== null) {
-            $len = strspn($this->string, $mask, $this->posByte, $length);
+        $out = "";
+        Process:
+        if ($this->mode === self::KATAKANA_STATE || $this->mode === self::LEAD_BYTE_STATE) {
+            // these modes will always return an empty span
         } else {
-            $len = strspn($this->string, $mask, $this->posByte);
+            if ($this->mode === self::ASCII_STATE) {
+                $exc = '/[\x0E\x0F\x1B\x80-\xFF]/s';
+            } elseif ($this->mode === self::ROMAN_STATE) {
+                $exc = '/[\x0E\x0F\x1B\x5C\x7E\x80-\xFF]/s';
+            } else {
+                // in other modes ASCII characters are never returned
+                return "";
+            }
+            $effectiveMask = preg_replace($exc, "", $mask);
+            if ($length !== null) {
+                $len = strspn($this->string, $effectiveMask, $this->posByte, $length);
+            } else {
+                $len = strspn($this->string, $effectiveMask, $this->posByte);
+            }
+            if ($len) {
+                $out .= substr($this->string, $this->posByte, $len);
+                $this->posByte += $len;
+                $this->posChar += $len;
+            }
         }
-        if ($len) {
-            $out = substr($this->string, $this->posByte, $len);
-            $this->posByte += $len;
-            $this->posChar += $len;
-            return $out;
-        } else {
-            return "";
+        // check if the current position has a mode change to ASCII or Roman modes and is followed by a desired character
+        if (@$this->string[$this->posByte] === "\x1B") {
+            if (substr($this->string, $this->posByte + 1, 2) === "\x28\x42") {
+                $exc = '/[\x0E\x0F\x1B\x80-\xFF]/s';
+            } elseif (substr($this->string, $this->posByte + 1, 2) === "\x28\x4A") {
+                $exc = '/[\x0E\x0F\x1B\x5C\x7E\x80-\xFF]/s';
+            } else {
+                return $out;
+            }
+            $effectiveMask = preg_replace($exc, "", $mask);
+            // if the byte after the mode switch is a wanted one, consume it and go back to the start
+            if (strspn(@$this->string[$this->posByte + 3], $effectiveMask, $this->posByte)) {
+                $out .= $this->nextChar();
+                goto Process;
+            }
         }
+        return $out;
     }
 
     public function asciiSpanNot(string $mask, int $length = null): string {