diff --git a/solr/CHANGES.txt b/solr/CHANGES.txt
index 134374951db..5e3939f4388 100644
--- a/solr/CHANGES.txt
+++ b/solr/CHANGES.txt
@@ -90,6 +90,10 @@ Bug Fixes
 
 * SOLR-3770: Overseer may lose updates to cluster state (siren)
 
+* SOLR-3721: Fix bug that could allow multiple recoveries to run briefly at
+  the same time if the recovery thread join call was interrupted.
+  (Per Steffensen, Mark Miller)
+
 Other Changes
 ----------------------
 
diff --git a/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java b/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java
index 6a53ed5e763..174e0d34114 100644
--- a/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java
+++ b/solr/core/src/java/org/apache/solr/update/DefaultSolrCoreState.java
@@ -242,10 +242,14 @@ public final class DefaultSolrCoreState extends SolrCoreState {
     synchronized (recoveryLock) {
       if (recoveryStrat != null) {
         recoveryStrat.close();
-        try {
-          recoveryStrat.join();
-        } catch (InterruptedException e) {
-          
+        while (true) {
+          try {
+            recoveryStrat.join();
+          } catch (InterruptedException e) {
+            // not interruptible - keep waiting
+            continue;
+          }
+          break;
         }
         
         recoveryRunning = false;