diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 26a9dec0014..b9deb7e1768 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -85,6 +85,11 @@ Bug Fixes
   the incoming automaton is a special case and throw a clearer
   exception than NullPointerException (Tom Mortimer via Mike McCandless)
 
+* LUCENE-6989: Fix Exception handling in MMapDirectory's unmap hack
+  support code to work with Java 9's new InaccessibleObjectException
+  that does not extend ReflectiveAccessException in Java 9.
+  (Uwe Schindler)
+
 Improvements
 
 * LUCENE-6824: TermAutomatonQuery now rewrites to TermQuery,
diff --git a/lucene/core/src/java/org/apache/lucene/store/MMapDirectory.java b/lucene/core/src/java/org/apache/lucene/store/MMapDirectory.java
index c0e35197f0e..be08a1663a6 100644
--- a/lucene/core/src/java/org/apache/lucene/store/MMapDirectory.java
+++ b/lucene/core/src/java/org/apache/lucene/store/MMapDirectory.java
@@ -385,13 +385,13 @@ public class MMapDirectory extends FSDirectory {
           }
         }
       };
-    } catch (ReflectiveOperationException e) {
-      return "Unmapping is not supported on this platform, because internal Java APIs are not compatible to this Lucene version: " + e; 
     } catch (SecurityException e) {
       return "Unmapping is not supported, because not all required permissions are given to the Lucene JAR file: " + e +
           " [Please grant at least the following permissions: RuntimePermission(\"accessClassInPackage.sun.misc\"), " +
           "RuntimePermission(\"accessClassInPackage.jdk.internal.ref\"), and " +
           "ReflectPermission(\"suppressAccessChecks\")]";
+    } catch (ReflectiveOperationException | RuntimeException e) {
+      return "Unmapping is not supported on this platform, because internal Java APIs are not compatible to this Lucene version: " + e; 
     }
   }