diff --git a/lib/deprecated/zbuff.h b/lib/deprecated/zbuff.h
index a968245b36a..b2f68312c5e 100644
--- a/lib/deprecated/zbuff.h
+++ b/lib/deprecated/zbuff.h
@@ -46,7 +46,7 @@ extern "C" {
 #else
 #  if defined (__cplusplus) && (__cplusplus >= 201402) /* C++14 or greater */
 #    define ZBUFF_DEPRECATED(message) [[deprecated(message)]] ZSTDLIB_API
-#  elif (defined(GNUC) && (GNUC > 4 || (GNUC == 4 && GNUC_MINOR >= 5))) || defined(__clang__)
+#  elif (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5))) || defined(__clang__)
 #    define ZBUFF_DEPRECATED(message) ZSTDLIB_API __attribute__((deprecated(message)))
 #  elif defined(__GNUC__) && (__GNUC__ >= 3)
 #    define ZBUFF_DEPRECATED(message) ZSTDLIB_API __attribute__((deprecated))
diff --git a/lib/zstd.h b/lib/zstd.h
index 97fef316fd6..8d01618205b 100644
--- a/lib/zstd.h
+++ b/lib/zstd.h
@@ -62,7 +62,7 @@ extern "C" {
 #else
 #  if defined (__cplusplus) && (__cplusplus >= 201402) /* C++14 or greater */
 #    define ZSTD_DEPRECATED(message) [[deprecated(message)]]
-#  elif (defined(GNUC) && (GNUC > 4 || (GNUC == 4 && GNUC_MINOR >= 5))) || defined(__clang__) || defined(__IAR_SYSTEMS_ICC__)
+#  elif (defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5))) || defined(__clang__) || defined(__IAR_SYSTEMS_ICC__)
 #    define ZSTD_DEPRECATED(message) __attribute__((deprecated(message)))
 #  elif defined(__GNUC__) && (__GNUC__ >= 3)
 #    define ZSTD_DEPRECATED(message) __attribute__((deprecated))