diff --git a/core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java b/core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java
index 33ba98c598..f299d598d0 100644
--- a/core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java
+++ b/core/src/main/java/jenkins/model/lazy/AbstractLazyLoadRunMap.java
@@ -585,6 +585,8 @@ public abstract class AbstractLazyLoadRunMap<R> extends AbstractMap<Integer,R> i
             numberOnDisk = a;
         }
 
+        entrySet.clearCache();
+
         return unwrap(old);
     }
 
@@ -742,6 +744,8 @@ public abstract class AbstractLazyLoadRunMap<R> extends AbstractMap<Integer,R> i
         BuildReference<R> old = copy.byId.remove(getIdOf(run));
         this.index = copy;
 
+        entrySet.clearCache();
+
         return unwrap(old)!=null;
     }
 
diff --git a/core/src/main/java/jenkins/model/lazy/LazyLoadRunMapEntrySet.java b/core/src/main/java/jenkins/model/lazy/LazyLoadRunMapEntrySet.java
index b3910b51ae..48aada93e0 100644
--- a/core/src/main/java/jenkins/model/lazy/LazyLoadRunMapEntrySet.java
+++ b/core/src/main/java/jenkins/model/lazy/LazyLoadRunMapEntrySet.java
@@ -32,6 +32,10 @@ class LazyLoadRunMapEntrySet<R> extends AbstractSet<Entry<Integer,R>> {
         return all;
     }
 
+    synchronized void clearCache() {
+        all = null;
+    }
+
     @Override
     public int size() {
         return all().size();
diff --git a/core/src/test/java/jenkins/model/lazy/AbstractLazyLoadRunMapTest.java b/core/src/test/java/jenkins/model/lazy/AbstractLazyLoadRunMapTest.java
index 55bd0bdfde..6cb55b6e7d 100644
--- a/core/src/test/java/jenkins/model/lazy/AbstractLazyLoadRunMapTest.java
+++ b/core/src/test/java/jenkins/model/lazy/AbstractLazyLoadRunMapTest.java
@@ -414,6 +414,13 @@ public class AbstractLazyLoadRunMapTest extends Assert {
         assertEquals(0, b.entrySet().size());
     }
 
+    @Issue("JENKINS-25655")
+    @Test public void entrySetChanges() {
+        assertEquals(3, a.entrySet().size());
+        a.put(new Build(7, "D"));
+        assertEquals(4, a.entrySet().size());
+    }
+
     @Issue("JENKINS-18065")
     @Test
     public void entrySetContains() {