diff --git a/WHATSNEW b/WHATSNEW
index f87562b20..3d4a39832 100644
--- a/WHATSNEW
+++ b/WHATSNEW
@@ -37,7 +37,11 @@ Fixed bugs:
    Bugzilla Report 48746
    
 *  SymlinkTest#testSymbolicLinkUtilsMethods failing on MacOS
-   Bugzilla Report 48785.        
+   Bugzilla Report 48785.
+
+*  If <concat>'s first resourcecollection child is a <resources>,
+   any subsequently added child resourcecollection joins the first.
+   Bugzilla Report 48816.        
 
 Other changes:
 --------------
diff --git a/src/main/org/apache/tools/ant/taskdefs/Concat.java b/src/main/org/apache/tools/ant/taskdefs/Concat.java
index a4e6b301c..9a8c433bf 100644
--- a/src/main/org/apache/tools/ant/taskdefs/Concat.java
+++ b/src/main/org/apache/tools/ant/taskdefs/Concat.java
@@ -465,7 +465,7 @@ public class Concat extends Task implements ResourceCollection {
      * Stores a collection of file sets and/or file lists, used to
      * select multiple files for concatenation.
      */
-    private ResourceCollection rc;
+    private Resources rc;
 
     /** for filtering the concatenated */
     private Vector filterChains;
@@ -634,19 +634,15 @@ public class Concat extends Task implements ResourceCollection {
      * @param c the ResourceCollection to add.
      * @since Ant 1.7
      */
-    public synchronized void add(ResourceCollection c) {
-        if (rc == null) {
-            rc = c;
-            return;
-        }
-        if (!(rc instanceof Resources)) {
-            Resources newRc = new Resources();
-            newRc.setProject(getProject());
-            newRc.setCache(true);
-            newRc.add(rc);
-            rc = newRc;
+    public void add(ResourceCollection c) {
+        synchronized (this) {
+            if (rc == null) {
+                rc = new Resources();
+                rc.setProject(getProject());
+                rc.setCache(true);
+            }
         }
-        ((Resources) rc).add(c);
+        rc.add(c);
     }
 
     /**