diff --git a/include/mbedtls/ecdsa.h b/include/mbedtls/ecdsa.h
index f991470..4897708 100644
--- a/include/mbedtls/ecdsa.h
+++ b/include/mbedtls/ecdsa.h
@@ -34,6 +34,11 @@
 #include "ecp.h"
 #include "md.h"
 
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
+#define inline __inline
+#endif
+
 /*
  * RFC-4492 page 20:
  *