diff --git a/src/lib/udeflate.cc b/src/lib/udeflate.cc
index c8f281f2ac4319a7cd358f852b383f6302996d4f..baab2089bd98c3f8e37e0ed4b7a8f58e78dac4ff 100644
--- a/src/lib/udeflate.cc
+++ b/src/lib/udeflate.cc
@@ -418,7 +418,7 @@ int8_t udeflate_zlib(unsigned char *input_buf, uint16_t input_len,
 		return UDEFLATE_ERR_METHOD;
 	}
 
-	if (zlib_flags & 0x10) {
+	if (zlib_flags & 0x20) {
 		return UDEFLATE_ERR_FDICT;
 	}