diff --git a/Changes b/Changes
index 56eb739..a522f7a 100644
--- a/Changes
+++ b/Changes
@@ -8,6 +8,8 @@
     - [bugfix] Fix StackOverflowError in ExpandedSpans by turning
       a recursive call into a loop
       (fixes #121; diewald; AI-assisted Claude Opus 4.6)
+    - [bugfix] Fix regex alternation in non-enclosed groups
+      (fixes #243; diewald; AI-assisted Claude Opus 4.6)
 
 0.64.6 2026-03-09
     - [performance] Add leaf cache. (diewald)
diff --git a/src/main/java/de/ids_mannheim/korap/KrillQuery.java b/src/main/java/de/ids_mannheim/korap/KrillQuery.java
index c71eb1a..ae21a82 100644
--- a/src/main/java/de/ids_mannheim/korap/KrillQuery.java
+++ b/src/main/java/de/ids_mannheim/korap/KrillQuery.java
@@ -1396,6 +1396,12 @@
                             return new SpanRepetitionQueryWrapper();
                         };
 
+                        // The regex contains a pipe and needs to be wrapped in a group
+                        if (offset > 0 && v.length() > offset
+                                && v.substring(offset).contains("|")) {
+                            v = v.substring(0, offset) + "(" + v.substring(offset) + ")";
+                        }
+
                         SpanRegexQueryWrapper srqw = qb.re(v, isCaseInsensitive);
 
                         if (srqw.error != null) {
diff --git a/src/test/java/de/ids_mannheim/korap/query/TestKrillQueryJSON.java b/src/test/java/de/ids_mannheim/korap/query/TestKrillQueryJSON.java
index a9758f0..4967eca 100644
--- a/src/test/java/de/ids_mannheim/korap/query/TestKrillQueryJSON.java
+++ b/src/test/java/de/ids_mannheim/korap/query/TestKrillQueryJSON.java
@@ -735,6 +735,19 @@
     };
 
     @Test
+    public void queryJSONregexAlternation () throws QueryException {
+        // /der|die/
+        String json = getJsonString(getClass()
+                .getResource("/queries/segment/regex-alternation.jsonld")
+                .getFile());
+        KrillQuery kq = new KrillQuery("tokens");
+
+        assertEquals(
+            "SpanMultiTermQueryWrapper(tokens:/s:(der|die)/)",
+            kq.fromKoral(json).toQuery().toString());
+    };
+
+    @Test
     public void queryJSONregexFail () {
         // "Leserin.{,3}"
         String json = getJsonString(getClass()
diff --git a/src/test/resources/queries/segment/regex-alternation.jsonld b/src/test/resources/queries/segment/regex-alternation.jsonld
new file mode 100644
index 0000000..9fb207e
--- /dev/null
+++ b/src/test/resources/queries/segment/regex-alternation.jsonld
@@ -0,0 +1,13 @@
+{
+  "query":{
+    "@type":"koral:token",
+    "wrap":{
+      "@type":"koral:term",
+      "match":"match:eq",
+      "type":"type:regex",
+      "layer":"orth",
+      "key":"der|die"
+    }
+  },
+  "@context":"http://korap.ids-mannheim.de/ns/koral/0.3/context.jsonld"
+}