diff --git a/src/main/java/org/jboss/netty/util/internal/jzlib/ZStream.java b/src/main/java/org/jboss/netty/util/internal/jzlib/ZStream.java
index 033cf88863..12b2372f9a 100644
--- a/src/main/java/org/jboss/netty/util/internal/jzlib/ZStream.java
+++ b/src/main/java/org/jboss/netty/util/internal/jzlib/ZStream.java
@@ -79,7 +79,8 @@ public final class ZStream {
         return inflateInit(w, WrapperType.ZLIB);
     }
 
-    public int inflateInit(int w, Enum<?> wrapperType) {
+    @SuppressWarnings("unchecked")
+    public int inflateInit(int w, Enum wrapperType) {
         istate = new Inflate();
         return istate.inflateInit(this, w, (WrapperType) wrapperType);
     }
@@ -118,7 +119,8 @@ public final class ZStream {
         return deflateInit(level, JZlib.MAX_WBITS);
     }
 
-    public int deflateInit(int level, Enum<?> wrapperType) {
+    @SuppressWarnings("unchecked")
+    public int deflateInit(int level, Enum wrapperType) {
         return deflateInit(level, JZlib.MAX_WBITS, wrapperType);
     }
 
@@ -126,7 +128,8 @@ public final class ZStream {
         return deflateInit(level, bits, WrapperType.ZLIB);
     }
 
-    public int deflateInit(int level, int bits, Enum<?> wrapperType) {
+    @SuppressWarnings("unchecked")
+    public int deflateInit(int level, int bits, Enum wrapperType) {
         dstate = new Deflate();
         return dstate.deflateInit(this, level, bits, (WrapperType) wrapperType);
     }