diff --git a/include/mbedtls/ecp.h b/include/mbedtls/ecp.h
index 0e2d47f..23ebe9b 100644
--- a/include/mbedtls/ecp.h
+++ b/include/mbedtls/ecp.h
@@ -42,6 +42,11 @@
 
 #include "mbedtls/bignum.h"
 
+#if (defined(__ARMCC_VERSION) || defined(_MSC_VER)) && \
+    !defined(inline) && !defined(__cplusplus)
+#define inline __inline
+#endif
+
 /*
  * ECP error codes
  */