diff --git a/nse_zlib.cc b/nse_zlib.cc
index 5a422ed7d..20cd6e0c6 100644
--- a/nse_zlib.cc
+++ b/nse_zlib.cc
@@ -961,8 +961,12 @@ LUALIB_API int luaopen_zlib(lua_State *L)
 
     PUSH_LITERAL(FILTERED)
     PUSH_LITERAL(HUFFMAN_ONLY)
+#ifdef Z_RLE
     PUSH_LITERAL(RLE)
+#endif
+#ifdef Z_FIXED
     PUSH_LITERAL(FIXED)
+#endif
     PUSH_LITERAL(DEFAULT_STRATEGY)
 
     PUSH_NUMBER(MINIMUM_MEMLEVEL, 1)