diff --git a/library/alignment.h b/library/alignment.h
index 4aab8e0..9e1e044 100644
--- a/library/alignment.h
+++ b/library/alignment.h
@@ -180,6 +180,16 @@
 #define MBEDTLS_BSWAP32 __rev
 #endif
 
+/* Detect IAR built-in byteswap routine */
+#if defined(__IAR_SYSTEMS_ICC__)
+#if defined(__ARM_ACLE)
+#include <arm_acle.h>
+#define MBEDTLS_BSWAP16(x) ((uint16_t) __rev16((uint32_t) (x)))
+#define MBEDTLS_BSWAP32 __rev
+#define MBEDTLS_BSWAP64 __revll
+#endif
+#endif
+
 /*
  * Where compiler built-ins are not present, fall back to C code that the
  * compiler may be able to detect and transform into the relevant bswap or
@@ -224,10 +234,25 @@
 #endif /* !defined(MBEDTLS_BSWAP64) */
 
 #if !defined(__BYTE_ORDER__)
+
+#if defined(__LITTLE_ENDIAN__)
+/* IAR defines __xxx_ENDIAN__, but not __BYTE_ORDER__ */
+#define MBEDTLS_IS_BIG_ENDIAN 0
+#elif defined(__BIG_ENDIAN__)
+#define MBEDTLS_IS_BIG_ENDIAN 1
+#else
 static const uint16_t mbedtls_byte_order_detector = { 0x100 };
 #define MBEDTLS_IS_BIG_ENDIAN (*((unsigned char *) (&mbedtls_byte_order_detector)) == 0x01)
+#endif
+
 #else
-#define MBEDTLS_IS_BIG_ENDIAN ((__BYTE_ORDER__) == (__ORDER_BIG_ENDIAN__))
+
+#if (__BYTE_ORDER__) == (__ORDER_BIG_ENDIAN__)
+#define MBEDTLS_IS_BIG_ENDIAN 1
+#else
+#define MBEDTLS_IS_BIG_ENDIAN 0
+#endif
+
 #endif /* !defined(__BYTE_ORDER__) */
 
 /**
diff --git a/library/ccm.c b/library/ccm.c
index 6700dc7..6b137d7 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -91,7 +91,7 @@
     }
 #endif
 
-    return 0;
+    return ret;
 }
 
 /*