diff --git a/sysdeps/x86_64/fpu/bits/fenv.h b/sysdeps/x86_64/fpu/bits/fenv.h
index 4af1643..d73859c 100644
--- a/sysdeps/x86_64/fpu/bits/fenv.h
+++ b/sysdeps/x86_64/fpu/bits/fenv.h
@@ -97,7 +97,7 @@ fenv_t;
 #endif
 
 
-#ifdef __OPTIMIZE__
+#ifdef __USE_EXTERN_INLINES
 __BEGIN_DECLS
 
 /* Optimized versions.  */