diff --git a/core/src/main/java/hudson/ClassicPluginStrategy.java b/core/src/main/java/hudson/ClassicPluginStrategy.java
index 3084ef796f..e46014f1a9 100644
--- a/core/src/main/java/hudson/ClassicPluginStrategy.java
+++ b/core/src/main/java/hudson/ClassicPluginStrategy.java
@@ -186,6 +186,10 @@ public class ClassicPluginStrategy implements PluginStrategy {
             } catch (InvalidPathException e) {
                 throw new IOException(e);
             }
+            String canonicalName = manifest.getMainAttributes().getValue("Short-Name") + ".jpi";
+            if (!archive.getName().equals(canonicalName)) {
+                LOGGER.warning(() -> "encountered " + archive + " under a nonstandard name; expected " + canonicalName);
+            }
         }
 
         final Attributes atts = manifest.getMainAttributes();
diff --git a/core/src/main/java/hudson/PluginManager.java b/core/src/main/java/hudson/PluginManager.java
index 266f7b48fa..ec4bd4b503 100644
--- a/core/src/main/java/hudson/PluginManager.java
+++ b/core/src/main/java/hudson/PluginManager.java
@@ -601,7 +601,7 @@ public abstract class PluginManager extends AbstractModelObject implements OnMas
     }
 
     void considerDetachedPlugin(String shortName) {
-        if (new File(rootDir, shortName + ".jpi").isFile()) {
+        if (new File(rootDir, shortName + ".jpi").isFile() || new File(rootDir, shortName + ".hpi").isFile()) {
             LOGGER.fine(() -> "not considering loading a detached dependency " + shortName + " as it is already on disk");
             return;
         }
diff --git a/test/src/test/java/jenkins/install/LoadDetachedPluginsTest.java b/test/src/test/java/jenkins/install/LoadDetachedPluginsTest.java
index f81549e85b..c5c51ddcc0 100644
--- a/test/src/test/java/jenkins/install/LoadDetachedPluginsTest.java
+++ b/test/src/test/java/jenkins/install/LoadDetachedPluginsTest.java
@@ -184,6 +184,20 @@ public class LoadDetachedPluginsTest {
         assertEquals(expectedPlugin, pw.getShortName());
     }
 
+    @Issue("JENKINS-55582")
+    @LocalData
+    @Test
+    public void nonstandardFilenames() {
+        logging.record(PluginManager.class, Level.FINE).record(ClassicPluginStrategy.class, Level.FINE);
+        rr.then(r -> {
+            assertTrue(r.jenkins.pluginManager.getPlugin("build-token-root").isActive());
+            assertEquals("1.2", r.jenkins.pluginManager.getPlugin("jdk-tool").getVersion());
+            /* TODO currently still loads the detached 1.0, since we only skip $shortName.[jh]pi not $shortName-$version.[jh]pi; during PLUGINS_LISTED there is a list of known filenames but not short names
+            assertEquals("1.3", r.jenkins.pluginManager.getPlugin("command-launcher").getVersion());
+            */
+        });
+    }
+
     private List<PluginWrapper> getInstalledDetachedPlugins(JenkinsRule r, List<DetachedPlugin> detachedPlugins) {
         PluginManager pluginManager = r.jenkins.getPluginManager();
         List<PluginWrapper> installedPlugins = new ArrayList<>();
diff --git a/test/src/test/resources/jenkins/install/LoadDetachedPluginsTest/nonstandardFilenames/plugins/build-token-root.jpi b/test/src/test/resources/jenkins/install/LoadDetachedPluginsTest/nonstandardFilenames/plugins/build-token-root.jpi
new file mode 100644
index 0000000000..17e86dc61c
Binary files /dev/null and b/test/src/test/resources/jenkins/install/LoadDetachedPluginsTest/nonstandardFilenames/plugins/build-token-root.jpi differ
diff --git a/test/src/test/resources/jenkins/install/LoadDetachedPluginsTest/nonstandardFilenames/plugins/command-launcher-1.3.hpi b/test/src/test/resources/jenkins/install/LoadDetachedPluginsTest/nonstandardFilenames/plugins/command-launcher-1.3.hpi
new file mode 100644
index 0000000000..9d36607ee6
Binary files /dev/null and b/test/src/test/resources/jenkins/install/LoadDetachedPluginsTest/nonstandardFilenames/plugins/command-launcher-1.3.hpi differ
diff --git a/test/src/test/resources/jenkins/install/LoadDetachedPluginsTest/nonstandardFilenames/plugins/jdk-tool.hpi b/test/src/test/resources/jenkins/install/LoadDetachedPluginsTest/nonstandardFilenames/plugins/jdk-tool.hpi
new file mode 100644
index 0000000000..3b32e40170
Binary files /dev/null and b/test/src/test/resources/jenkins/install/LoadDetachedPluginsTest/nonstandardFilenames/plugins/jdk-tool.hpi differ