diff --git a/CHANGELOG.md b/CHANGELOG.md
index a193dce..d767074 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,12 @@
 # Changelog
 
 
+## 2.4.2 [2026-06-16]
+
+* Fixed a crash (`pushback value was too large`) on German gender-sensitive forms
+  separated by a non-ASCII slash — division slash (U+2215 `∕`), fraction slash
+  (U+2044 `⁄`) or fullwidth solidus (U+FF0F `／`) — which could occur on EPUB input
+
 ## 2.4.1 [2026-04-03]
 
 * Fixed Unicode surrogate pair handling bugs in German gender sensitive forms
diff --git a/src/main/jpc/jflex/de/ids_mannheim/korap/tokenizer/DerekoDfaTokenizer.jflex b/src/main/jpc/jflex/de/ids_mannheim/korap/tokenizer/DerekoDfaTokenizer.jflex
index 58bbf28..afad9ee 100644
--- a/src/main/jpc/jflex/de/ids_mannheim/korap/tokenizer/DerekoDfaTokenizer.jflex
+++ b/src/main/jpc/jflex/de/ids_mannheim/korap/tokenizer/DerekoDfaTokenizer.jflex
@@ -405,6 +405,23 @@
     }
 
     /**
+     * Find the last index of a SLASH-class separator. MUST stay in sync with the
+     * SLASH macro ([/⁄∕／]): matched.lastIndexOf('/') alone misses the non-ASCII
+     * variants (U+2044, U+2215, U+FF0F); for those it returns -1, which made
+     * yypushback(length - (-1)) overflow and throw "pushback value was too large"
+     * on gender-slash forms (e.g. "Lehrer∕innenx").
+     */
+    private static int lastIndexOfSlash(String s) {
+        for (int i = s.length() - 1; i >= 0; i--) {
+            char c = s.charAt(i);
+            if (c == '/' || c == '⁄' || c == '∕' || c == '／') {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    /**
      * Handle gender short suffix with colon separator.
      * Pattern: {WORD}:{suffix}{lookahead}
      * If lookahead is a letter, return just WORD, pushing back the rest.
@@ -439,7 +456,7 @@
         int lastChar = matched.codePointBefore(matched.length());
         
         // Find the slash position
-        int slashPos = matched.lastIndexOf('/');
+        int slashPos = lastIndexOfSlash(matched);
         
         if (isLetter(lastChar)) {
             // Followed by a letter - not a valid gender form
@@ -521,7 +538,7 @@
         int lastChar = matched.codePointBefore(matched.length());
         
         // Find the slash position
-        int slashPos = matched.lastIndexOf('/');
+        int slashPos = lastIndexOfSlash(matched);
         
         if (isLetter(lastChar)) {
             // Followed by a letter - not a valid gender form
diff --git a/src/test/java/de/ids_mannheim/korap/tokenizer/TokenizerTest.java b/src/test/java/de/ids_mannheim/korap/tokenizer/TokenizerTest.java
index 8ad27c2..1499f76 100644
--- a/src/test/java/de/ids_mannheim/korap/tokenizer/TokenizerTest.java
+++ b/src/test/java/de/ids_mannheim/korap/tokenizer/TokenizerTest.java
@@ -926,6 +926,31 @@
     }
 
     @Test
+    public void testGenderSensitiveSlashFormsWithUnicodeSlash() {
+        // Regression: the SLASH macro matches four characters (/ ⁄ ∕ ／), but the
+        // gender-slash handlers located the separator with matched.lastIndexOf('/'),
+        // which returns -1 for the non-ASCII variants. That made yypushback compute
+        // length-(-1) and throw "pushback value was too large" (crash on real epub
+        // input, e.g. DNB25). See genderSlashSuffixToken/genderNounSlashToken.
+        DerekoDfaTokenizer_de tok = new DerekoDfaTokenizer_de();
+
+        // Valid Unicode-slash gender form (non-letter lookahead) is kept as one
+        // token, exactly like its ASCII counterpart:
+        String[] tokens = tok.tokenize("Lehrer∕innen kamen.");  // U+2215 DIVISION SLASH
+        assertEquals("Lehrer∕innen", tokens[0]);
+        assertEquals("kamen", tokens[1]);
+        assertEquals(".", tokens[2]);
+        assertEquals(3, tokens.length);
+
+        // Crash cases (genderSlashSuffixToken): a non-ASCII slash + short gender
+        // suffix + letter lookahead must not overflow the pushback. The stem, the
+        // slash and the remainder are all emitted (no character is lost):
+        assertArrayEquals(new String[]{"Auto", "∕", "nn"}, tok.tokenize("Auto∕nn")); // U+2215
+        assertArrayEquals(new String[]{"Gerd", "⁄", "ss"}, tok.tokenize("Gerd⁄ss")); // U+2044
+        assertArrayEquals(new String[]{"Tag", "／", "rr"}, tok.tokenize("Tag／rr"));   // U+FF0F
+    }
+
+    @Test
     public void testGenderSensitiveParentheticalForms() {
         DerekoDfaTokenizer_de tok = new DerekoDfaTokenizer_de();