diff --git a/WHATSNEW b/WHATSNEW
index 360578c64..75d04dc34 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -226,6 +226,9 @@ Fixed bugs:
    than numbers, letters, hyphen or underscore properly.
    Bugzilla Report 45820.
 
+ * <filterset> could miss multi-character begin tokens in some cases.
+   Bugzilla Report 45094.
+
 Other changes:
 --------------
 
diff --git a/src/main/org/apache/tools/ant/types/FilterSet.java b/src/main/org/apache/tools/ant/types/FilterSet.java
index 63c829886..ee322d974 100644
--- a/src/main/org/apache/tools/ant/types/FilterSet.java
+++ b/src/main/org/apache/tools/ant/types/FilterSet.java
@@ -537,9 +537,13 @@ public class FilterSet extends DataType implements Cloneable {
                         i = index + beginToken.length() + token.length()
                             + endToken.length();
                     } else {
-                        // just append beginToken and search further
-                        b.append(beginToken);
-                        i = index + beginToken.length();
+                        // just append first character of beginToken
+                        // and search further
+                        // we can't skip the complete beginToken since
+                        // it may contain the start of another
+                        // candidate begin token (Bugzilla 45094)
+                        b.append(beginToken.charAt(0));
+                        i = index + 1;
                     }
                     index = line.indexOf(beginToken, i);
                 }
diff --git a/src/tests/antunit/types/filterset-test.xml b/src/tests/antunit/types/filterset-test.xml
index 99c2e152b..506f3be1a 100644
--- a/src/tests/antunit/types/filterset-test.xml
+++ b/src/tests/antunit/types/filterset-test.xml
@@ -41,4 +41,23 @@
        actual="${afterfiltering}"/>
   </target>
 
+  <!-- https://issues.apache.org/bugzilla/show_bug.cgi?id=45094 -->
+  <target name="testOverlappingMulticharToken">
+    <mkdir dir="${output}"/>
+    <copy todir="${output}">
+      <string value="@@USER@@@@@HOST@@" />
+      <mergemapper to="filterset-output.txt" />
+      <filterset begintoken="@@" endtoken="@@">
+        <filter token="USER" value="user" />
+        <filter token="HOST" value="host" />
+      </filterset>
+    </copy>
+
+    <loadfile property="afterfiltering" srcFile="${output}/filterset-output.txt"/>
+
+    <au:assertEquals
+       expected="user@host"
+       actual="${afterfiltering}"/>
+  </target>
+
 </project>