diff --git a/include/polarssl/cipher.h b/include/polarssl/cipher.h
index dc5a41c..b7d4492 100644
--- a/include/polarssl/cipher.h
+++ b/include/polarssl/cipher.h
@@ -30,6 +30,12 @@
 #ifndef POLARSSL_CIPHER_H
 #define POLARSSL_CIPHER_H
 
+#include "config.h"
+
+#if defined(POLARSSL_GCM_C)
+#define POLARSSL_CIPHER_MODE_AEAD
+#endif
+
 #include <string.h>
 
 #if defined(_MSC_VER) && !defined(inline)
@@ -457,15 +463,13 @@
  * \brief               Finish preparation of the given context
  *
  * \param ctx           generic cipher context
- * \param ad            Additional data for AEAD ciphers, or discarded.
- *                      May be NULL only if ad_len is 0.
- * \param ad_len        Length of ad for AEAD ciphers, or discarded.
  *
  * \returns             0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA
  *                      if parameter verification fails.
  */
 int cipher_reset( cipher_context_t *ctx );
 
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
 /**
  * \brief               Add additional data (for AEAD ciphers).
  *                      This function has no effect for non-AEAD ciphers.
@@ -483,6 +487,7 @@
  */
 int cipher_update_ad( cipher_context_t *ctx,
                       const unsigned char *ad, size_t ad_len );
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
 /**
  * \brief               Generic cipher update function. Encrypts/decrypts
@@ -530,6 +535,7 @@
 int cipher_finish( cipher_context_t *ctx,
                    unsigned char *output, size_t *olen );
 
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
 /**
  * \brief               Write tag for AEAD ciphers.
  *                      No effect for other ciphers.
@@ -556,6 +562,7 @@
  */
 int cipher_check_tag( cipher_context_t *ctx,
                       const unsigned char *tag, size_t tag_len );
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
 /**
  * \brief          Checkup routine
diff --git a/library/cipher.c b/library/cipher.c
index a90e2dc..160f4bc 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -425,6 +425,7 @@
     return 0;
 }
 
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
 int cipher_update_ad( cipher_context_t *ctx,
                       const unsigned char *ad, size_t ad_len )
 {
@@ -444,13 +445,11 @@
         return gcm_starts( ctx->cipher_ctx, ctx->operation,
                            ctx->iv, ctx->iv_size, ad, ad_len );
     }
-#else
-    ((void) ad);
-    ((void) ad_len);
 #endif
 
     return 0;
 }
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
 int cipher_update( cipher_context_t *ctx, const unsigned char *input, size_t ilen,
         unsigned char *output, size_t *olen )
@@ -904,50 +903,62 @@
     return 0;
 }
 
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
 int cipher_write_tag( cipher_context_t *ctx,
                       unsigned char *tag, size_t tag_len )
 {
     if( NULL == ctx || NULL == ctx->cipher_info || NULL == tag )
         return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
 
-    if( POLARSSL_MODE_GCM != ctx->cipher_info->mode )
-        return( 0 );
-
     if( POLARSSL_ENCRYPT != ctx->operation )
         return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
 
-    return gcm_finish( ctx->cipher_ctx, tag, tag_len );
+#if defined(POLARSSL_GCM_C)
+    if( POLARSSL_MODE_GCM == ctx->cipher_info->mode )
+        return gcm_finish( ctx->cipher_ctx, tag, tag_len );
+#endif
+
+    return 0;
 }
  
 int cipher_check_tag( cipher_context_t *ctx,
                       const unsigned char *tag, size_t tag_len )
 {
     int ret;
-    unsigned char check_tag[16];
-    size_t i;
-    int diff;
 
-    if( NULL == ctx || NULL == ctx->cipher_info )
+    if( NULL == ctx || NULL == ctx->cipher_info ||
+        POLARSSL_DECRYPT != ctx->operation )
+    {
         return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
+    }
 
-    if( POLARSSL_MODE_GCM != ctx->cipher_info->mode )
+#if defined(POLARSSL_GCM_C)
+    if( POLARSSL_MODE_GCM == ctx->cipher_info->mode )
+    {
+        unsigned char check_tag[16];
+        size_t i;
+        int diff;
+
+        if( tag_len > sizeof( check_tag ) )
+            return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
+
+        if( 0 != ( ret = gcm_finish( ctx->cipher_ctx, check_tag, tag_len ) ) )
+            return( ret );
+
+        /* Check the tag in "constant-time" */
+        for( diff = 0, i = 0; i < tag_len; i++ )
+            diff |= tag[i] ^ check_tag[i];
+
+        if( diff != 0 )
+            return( POLARSSL_ERR_GCM_AUTH_FAILED );
+
         return( 0 );
-
-    if( POLARSSL_DECRYPT != ctx->operation || tag_len > sizeof( check_tag ) )
-        return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
-
-    if( 0 != ( ret = gcm_finish( ctx->cipher_ctx, check_tag, tag_len ) ) )
-        return( ret );
-
-    /* On decryption, check the tag (in "constant-time") */
-    for( diff = 0, i = 0; i < tag_len; i++ )
-        diff |= tag[i] ^ check_tag[i];
-
-    if( diff != 0 )
-        return( POLARSSL_ERR_GCM_AUTH_FAILED );
+    }
+#endif
 
     return( 0 );
 }
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
 #if defined(POLARSSL_SELF_TEST)
 
diff --git a/tests/suites/test_suite_cipher.function b/tests/suites/test_suite_cipher.function
index 5d32bc3..63de2db 100644
--- a/tests/suites/test_suite_cipher.function
+++ b/tests/suites/test_suite_cipher.function
@@ -64,8 +64,10 @@
     TEST_ASSERT( 0 == cipher_reset( &ctx_dec ) );
     TEST_ASSERT( 0 == cipher_reset( &ctx_enc ) );
 
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
     TEST_ASSERT( 0 == cipher_update_ad( &ctx_dec, ad, 13 ) );
     TEST_ASSERT( 0 == cipher_update_ad( &ctx_enc, ad, 13 ) );
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
     /* encode length number of bytes from inbuf */
     TEST_ASSERT( 0 == cipher_update( &ctx_enc, inbuf, length, encbuf, &outlen ) );
@@ -79,7 +81,9 @@
     TEST_ASSERT( 0 == cipher_finish( &ctx_enc, encbuf + outlen, &outlen ) );
     total_len += outlen;
 
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
     TEST_ASSERT( 0 == cipher_write_tag( &ctx_enc, tag, 16 ) );
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
     TEST_ASSERT( total_len == length ||
                  ( total_len % cipher_get_block_size( &ctx_enc ) == 0 &&
@@ -98,7 +102,9 @@
     TEST_ASSERT( 0 == cipher_finish( &ctx_dec, decbuf + outlen, &outlen ) );
     total_len += outlen;
 
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
     TEST_ASSERT( 0 == cipher_check_tag( &ctx_dec, tag, 16 ) );
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
     TEST_ASSERT( total_len == length );
 
@@ -143,7 +149,9 @@
     TEST_ASSERT( 0 == cipher_set_padding_mode( &ctx, pad_mode ) );
     TEST_ASSERT( 0 == cipher_set_iv( &ctx, iv, 16 ) );
     TEST_ASSERT( 0 == cipher_reset( &ctx ) );
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
     TEST_ASSERT( 0 == cipher_update_ad( &ctx, NULL, 0 ) );
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
     /* encode length number of bytes from inbuf */
     TEST_ASSERT( 0 == cipher_update( &ctx, inbuf, length, encbuf, &outlen ) );
@@ -188,7 +196,9 @@
 
     TEST_ASSERT( 0 == cipher_reset( &ctx_dec ) );
 
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
     TEST_ASSERT( 0 == cipher_update_ad( &ctx_dec, NULL, 0 ) );
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
     /* decode 0-byte string */
     TEST_ASSERT( 0 == cipher_update( &ctx_dec, encbuf, 0, decbuf, &outlen ) );
@@ -248,8 +258,10 @@
     TEST_ASSERT( 0 == cipher_reset( &ctx_dec ) );
     TEST_ASSERT( 0 == cipher_reset( &ctx_enc ) );
 
+#if defined(POLARSSL_CIPHER_MODE_AEAD)
     TEST_ASSERT( 0 == cipher_update_ad( &ctx_dec, NULL, 0 ) );
     TEST_ASSERT( 0 == cipher_update_ad( &ctx_enc, NULL, 0 ) );
+#endif /* POLARSSL_CIPHER_MODE_AEAD */
 
     /* encode length number of bytes from inbuf */
     TEST_ASSERT( 0 == cipher_update( &ctx_enc, inbuf, first_length, encbuf, &outlen ) );