diff --git a/include/mbedtls/bn_mul.h b/include/mbedtls/bn_mul.h
index 4200ad43a..163869ae7 100644
--- a/include/mbedtls/bn_mul.h
+++ b/include/mbedtls/bn_mul.h
@@ -204,20 +204,20 @@
     asm(
 
 #define MULADDC_CORE                \
-        "ldr x4, [%3], #8   \n\t"   \
-        "ldr x5, [%4]       \n\t"   \
-        "mul x6, x4, %6     \n\t"   \
-        "umulh x7, x4, %6   \n\t"   \
+        "ldr x4, [%2], #8   \n\t"   \
+        "ldr x5, [%1]       \n\t"   \
+        "mul x6, x4, %3     \n\t"   \
+        "umulh x7, x4, %3   \n\t"   \
         "adds x5, x5, x6    \n\t"   \
         "adc x7, x7, xzr    \n\t"   \
-        "adds x5, x5, %5    \n\t"   \
+        "adds x5, x5, %0    \n\t"   \
         "adc %0, x7, xzr    \n\t"   \
         "str x5, [%1], #8   \n\t"
 
-#define MULADDC_STOP                            \
-         : "+r" (c),  "=r" (d), "=r" (s)        \
-         : "r" (s), "r" (d), "r" (c), "r" (b)   \
-         : "x4", "x5", "x6", "x7", "cc"         \
+#define MULADDC_STOP                        \
+         : "+r" (c),  "+r" (d), "+r" (s)    \
+         : "r" (b)                          \
+         : "x4", "x5", "x6", "x7", "cc"     \
     );
 
 #endif /* Aarch64 */