diff --git a/Utilities/cmbzip2/bzlib.c b/Utilities/cmbzip2/bzlib.c
index baed28849..aeecef10f 100644
--- a/Utilities/cmbzip2/bzlib.c
+++ b/Utilities/cmbzip2/bzlib.c
@@ -102,6 +102,7 @@ static
 void* default_bzalloc ( void* opaque, Int32 items, Int32 size )
 {
    void* v = malloc ( items * size );
+  (void)opaque;
    return v;
 }
 
@@ -109,6 +110,7 @@ static
 void default_bzfree ( void* opaque, void* addr )
 {
    if (addr != NULL) free ( addr );
+  (void)opaque;
 }
 
 
@@ -1505,6 +1507,7 @@ int BZ_API(BZ2_bzwrite) (BZFILE* b, void* buf, int len )
 /*---------------------------------------------------*/
 int BZ_API(BZ2_bzflush) (BZFILE *b)
 {
+  (void) b;
    /* do nothing now... */
    return 0;
 }