diff --git a/wolfssl/wolfcrypt/settings.h b/wolfssl/wolfcrypt/settings.h
index 38f6ba290..3072906a8 100644
--- a/wolfssl/wolfcrypt/settings.h
+++ b/wolfssl/wolfcrypt/settings.h
@@ -2123,9 +2123,17 @@ extern void uITRON4_free(void *p) ;
     #include "RTOS.h"
     #if !defined(XMALLOC_USER) && !defined(NO_WOLFSSL_MEMORY) && \
         !defined(WOLFSSL_STATIC_MEMORY)
-        #define XMALLOC(s, h, type)  ((void)(h), (void)(type), OS_HEAP_malloc((s)))
-        #define XFREE(p, h, type)    ((void)(h), (void)(type), OS_HEAP_free((p)))
-        #define XREALLOC(p, n, h, t) ((void)(h), (void)(t), OS_HEAP_realloc(((p), (n)))
+        /* Per the user manual of embOS https://www.segger.com/downloads/embos/UM01001
+         * this API has changed with V5. */
+        #if (OS_VERSION >= 50000U)
+            #define XMALLOC(s, h, type)  ((void)(h), (void)(type), OS_HEAP_malloc((s)))
+            #define XFREE(p, h, type)    ((void)(h), (void)(type), OS_HEAP_free((p)))
+            #define XREALLOC(p, n, h, t) ((void)(h), (void)(t), OS_HEAP_realloc((p), (n)))
+        #else
+            #define XMALLOC(s, h, type)  ((void)(h), (void)(type), OS_malloc((s)))
+            #define XFREE(p, h, type)    ((void)(h), (void)(type), OS_free((p)))
+            #define XREALLOC(p, n, h, t) ((void)(h), (void)(t), OS_realloc((p), (n)))
+        #endif
     #endif
 #endif
 
diff --git a/wolfssl/wolfcrypt/types.h b/wolfssl/wolfcrypt/types.h
index 692f11337..1abdfb9a3 100644
--- a/wolfssl/wolfcrypt/types.h
+++ b/wolfssl/wolfcrypt/types.h
@@ -558,6 +558,10 @@ typedef struct w64wrapper {
                 #endif
                 #define XREALLOC(p, n, h, t) wolfSSL_Realloc((p), (n), (h), (t))
             #endif /* WOLFSSL_DEBUG_MEMORY */
+        #elif  defined(WOLFSSL_EMBOS) && !defined(XMALLOC_USER) \
+                && !defined(NO_WOLFSSL_MEMORY) \
+                && !defined(WOLFSSL_STATIC_MEMORY)
+            /* settings.h solve this case already. Avoid redefinition. */
         #elif (!defined(FREERTOS) && !defined(FREERTOS_TCP)) || defined(WOLFSSL_TRACK_MEMORY)
             #ifdef WOLFSSL_DEBUG_MEMORY
                 #define XMALLOC(s, h, t)     ((void)(h), (void)(t), wolfSSL_Malloc((s), __func__, __LINE__))