diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 49c3120..3d8a5ea 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -30,6 +30,11 @@
 
 #include <stddef.h>
 
+#if ( defined(__ARMCC_VERSION) || defined(_MSC_VER) ) && \
+    !defined(inline) && !defined(__cplusplus)
+#define inline __inline
+#endif
+
 /**
  * Error code layout.
  *