diff --git a/lib/atomic.h b/lib/atomic.h
index 2f4ab045..3d6defda 100644
--- a/lib/atomic.h
+++ b/lib/atomic.h
@@ -100,8 +100,8 @@ using std::atomic_fetch_and_explicit;
 using std::atomic_thread_fence;
 using std::atomic_signal_fence;
 
-#elif defined(HAVE_STDATOMIC_H) && !defined(__CC_ARM) && !defined(__arm__) && \
-      !defined(__STDC_NO_ATOMICS__)
+#elif defined(HAVE_STDATOMIC_H) && !defined(__STDC_NO_ATOMICS__) && \
+(!defined(__ARMCC_VERSION) || defined(__GNUC__))
 # include <stdint.h>
 # include <stdatomic.h>
 #elif defined(__GNUC__)
diff --git a/lib/errno.h b/lib/errno.h
index 2fc4f77a..fa8270db 100644
--- a/lib/errno.h
+++ b/lib/errno.h
@@ -14,7 +14,7 @@
 
 #if defined(__ICCARM__)
 # include <metal/compiler/iar/errno.h>
-#elif defined(__CC_ARM) || defined(__arm__)
+#elif defined(__ARMCC_VERSION)
 # include <metal/compiler/armcc/errno.h>
 #else
 # include <errno.h>