diff --git a/library/aesni.c b/library/aesni.c
index 0c509ac..6c917da 100644
--- a/library/aesni.c
+++ b/library/aesni.c
@@ -93,7 +93,6 @@
     ++rk;
     --nr;
 
-#if !defined(MBEDTLS_BLOCK_CIPHER_NO_DECRYPT)
     if (mode == MBEDTLS_AES_ENCRYPT) {
         while (nr != 0) {
             state = _mm_aesenc_si128(state, *rk);
@@ -102,23 +101,17 @@
         }
         state = _mm_aesenclast_si128(state, *rk);
     } else {
+#if !defined(MBEDTLS_BLOCK_CIPHER_NO_DECRYPT)
         while (nr != 0) {
             state = _mm_aesdec_si128(state, *rk);
             ++rk;
             --nr;
         }
         state = _mm_aesdeclast_si128(state, *rk);
-    }
 #else
-    (void) mode;
-    while (nr != 0) {
-
-        state = _mm_aesenc_si128(state, *rk);
-        ++rk;
-        --nr;
+        return MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE;
+#endif
     }
-    state = _mm_aesenclast_si128(state, *rk);
-#endif /* !MBEDTLS_BLOCK_CIPHER_NO_DECRYPT */
 
     memcpy(output, &state, 16);
     return 0;
@@ -452,6 +445,12 @@
                             const unsigned char input[16],
                             unsigned char output[16])
 {
+#if defined(MBEDTLS_BLOCK_CIPHER_NO_DECRYPT)
+    if (mode == MBEDTLS_AES_DECRYPT) {
+        return MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE;
+    }
+#endif
+
     asm ("movdqu    (%3), %%xmm0    \n\t" // load input
          "movdqu    (%1), %%xmm1    \n\t" // load round key 0
          "pxor      %%xmm1, %%xmm0  \n\t" // round 0