diff --git a/library/timing.c b/library/timing.c
index 4ff11e7..bdbdcce 100644
--- a/library/timing.c
+++ b/library/timing.c
@@ -39,6 +39,10 @@
 
 #if !defined(MBEDTLS_TIMING_ALT)
 
+#ifndef asm
+#define asm __asm
+#endif
+
 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
 
 #include <windows.h>