diff --git a/lib/common/compiler.h b/lib/common/compiler.h
index 2f18efb0a..95e948352 100644
--- a/lib/common/compiler.h
+++ b/lib/common/compiler.h
@@ -17,7 +17,7 @@
 /* force inlining */
 
 #if !defined(ZSTD_NO_INLINE)
-#if defined (__GNUC__) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L   /* C99 */
+#if (defined(__GNUC__) && !defined(__STRICT_ANSI__)) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L   /* C99 */
 #  define INLINE_KEYWORD inline
 #else
 #  define INLINE_KEYWORD
diff --git a/lib/common/xxhash.c b/lib/common/xxhash.c
index 429a869e9..72314c59f 100644
--- a/lib/common/xxhash.c
+++ b/lib/common/xxhash.c
@@ -95,7 +95,7 @@ static void* XXH_memcpy(void* dest, const void* src, size_t size) { return memcp
 /* *************************************
 *  Compiler Specific Options
 ***************************************/
-#if defined (__GNUC__) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L   /* C99 */
+#if (defined(__GNUC__) && !defined(__STRICT_ANSI__)) || defined(__cplusplus) || defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L   /* C99 */
 #  define INLINE_KEYWORD inline
 #else
 #  define INLINE_KEYWORD