diff --git a/solr/CHANGES.txt b/solr/CHANGES.txt
index 18219d41643..2e1c70dda1f 100644
--- a/solr/CHANGES.txt
+++ b/solr/CHANGES.txt
@@ -148,6 +148,9 @@ Bug Fixes
 * SOLR-11297: Message "Lock held by this virtual machine" during startup.  Solr is trying to start some cores twice.
   (Luiz Armesto, Shawn Heisey, Erick Erickson)
 
+* SOLR-11399: The UnifiedHighlighter was ignoring the hl.fragsize parameter when hl.bs.type=SEPARATOR
+  (Marc Morissette via David Smiley)
+
 
 Optimizations
 ----------------------
diff --git a/solr/core/src/java/org/apache/solr/highlight/UnifiedSolrHighlighter.java b/solr/core/src/java/org/apache/solr/highlight/UnifiedSolrHighlighter.java
index 48cb874f499..a4beaba5a33 100644
--- a/solr/core/src/java/org/apache/solr/highlight/UnifiedSolrHighlighter.java
+++ b/solr/core/src/java/org/apache/solr/highlight/UnifiedSolrHighlighter.java
@@ -310,15 +310,19 @@ public class UnifiedSolrHighlighter extends SolrHighlighter implements PluginInf
       String type = params.getFieldParam(field, HighlightParams.BS_TYPE);
       if (fragsize == 0 || "WHOLE".equals(type)) { // 0 is special value; no fragmenting
         return new WholeBreakIterator();
-      } else if ("SEPARATOR".equals(type)) {
-        char customSep = parseBiSepChar(params.getFieldParam(field, HighlightParams.BS_SEP));
-        return new CustomSeparatorBreakIterator(customSep);
       }
-      String language = params.getFieldParam(field, HighlightParams.BS_LANGUAGE);
-      String country = params.getFieldParam(field, HighlightParams.BS_COUNTRY);
-      String variant = params.getFieldParam(field, HighlightParams.BS_VARIANT);
-      Locale locale = parseLocale(language, country, variant);
-      BreakIterator baseBI = parseBreakIterator(type, locale);
+
+      BreakIterator baseBI;
+      if ("SEPARATOR".equals(type)) {
+        char customSep = parseBiSepChar(params.getFieldParam(field, HighlightParams.BS_SEP));
+        baseBI = new CustomSeparatorBreakIterator(customSep);
+      } else {
+        String language = params.getFieldParam(field, HighlightParams.BS_LANGUAGE);
+        String country = params.getFieldParam(field, HighlightParams.BS_COUNTRY);
+        String variant = params.getFieldParam(field, HighlightParams.BS_VARIANT);
+        Locale locale = parseLocale(language, country, variant);
+        baseBI = parseBreakIterator(type, locale);
+      }
 
       if (fragsize <= 1) { // no real minimum size
         return baseBI;
diff --git a/solr/core/src/test/org/apache/solr/highlight/TestUnifiedSolrHighlighter.java b/solr/core/src/test/org/apache/solr/highlight/TestUnifiedSolrHighlighter.java
index ad1ca0336ef..aeffed1f69d 100644
--- a/solr/core/src/test/org/apache/solr/highlight/TestUnifiedSolrHighlighter.java
+++ b/solr/core/src/test/org/apache/solr/highlight/TestUnifiedSolrHighlighter.java
@@ -256,6 +256,9 @@ public class TestUnifiedSolrHighlighter extends SolrTestCaseJ4 {
         req("q", "text:document", "sort", "id asc", "hl", "true", "hl.bs.type", "SEPARATOR","hl.bs.separator","#","hl.fragsize", "-1"),
         "//lst[@name='highlighting']/lst[@name='104']/arr[@name='text']/str='While the other <em>document</em> contains the same #'");
 
+    assertQ("CUSTOM breakiterator with fragsize 70",
+        req("q", "text:document", "sort", "id asc", "hl", "true", "hl.bs.type", "SEPARATOR","hl.bs.separator","#","hl.fragsize", "70"),
+        "//lst[@name='highlighting']/lst[@name='103']/arr[@name='text']/str='This <em>document</em> contains # special characters, while the other <em>document</em> contains the same #'");
   }
 
   public void testFragsize() {