diff --git a/pom.xml b/pom.xml
index c067169138..dd268a985e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -88,25 +88,25 @@
               <Specification-Title>Bukkit</Specification-Title>
               <Specification-Version>${api.version}</Specification-Version>
               <Specification-Vendor>Bukkit Team</Specification-Vendor>
-              <Sealed>false</Sealed>
+              <Sealed>true</Sealed>
             </manifestEntries>
             <manifestSections>
               <manifestSection>
                 <name>net/bukkit/</name>
                 <manifestEntries>
-                  <Sealed>false</Sealed>
+                  <Sealed>true</Sealed>
                 </manifestEntries>
               </manifestSection>
               <manifestSection>
                 <name>com/bukkit/</name>
                 <manifestEntries>
-                  <Sealed>false</Sealed>
+                  <Sealed>true</Sealed>
                 </manifestEntries>
               </manifestSection>
               <manifestSection>
                 <name>org/bukkit/</name>
                 <manifestEntries>
-                  <Sealed>false</Sealed>
+                  <Sealed>true</Sealed>
                 </manifestEntries>
               </manifestSection>
             </manifestSections>