diff --git a/tests/suites/test_suite_aes.ctr.data b/tests/suites/test_suite_aes.ctr.data
new file mode 100644
index 0000000..6ce7c01
--- /dev/null
+++ b/tests/suites/test_suite_aes.ctr.data
@@ -0,0 +1,119 @@
+AES-CTR aes_encrypt_ctr_multipart 1 1
+aes_encrypt_ctr_multipart:1:1
+
+AES-CTR aes_encrypt_ctr_multipart 2 1
+aes_encrypt_ctr_multipart:2:1
+
+AES-CTR aes_encrypt_ctr_multipart 2 2
+aes_encrypt_ctr_multipart:2:2
+
+AES-CTR aes_encrypt_ctr_multipart 4 1
+aes_encrypt_ctr_multipart:4:1
+
+AES-CTR aes_encrypt_ctr_multipart 4 2
+aes_encrypt_ctr_multipart:4:2
+
+AES-CTR aes_encrypt_ctr_multipart 15 1
+aes_encrypt_ctr_multipart:15:1
+
+AES-CTR aes_encrypt_ctr_multipart 15 2
+aes_encrypt_ctr_multipart:15:2
+
+AES-CTR aes_encrypt_ctr_multipart 15 8
+aes_encrypt_ctr_multipart:15:8
+
+AES-CTR aes_encrypt_ctr_multipart 15 15
+aes_encrypt_ctr_multipart:15:15
+
+AES-CTR aes_encrypt_ctr_multipart 16 1
+aes_encrypt_ctr_multipart:16:1
+
+AES-CTR aes_encrypt_ctr_multipart 16 2
+aes_encrypt_ctr_multipart:16:2
+
+AES-CTR aes_encrypt_ctr_multipart 16 8
+aes_encrypt_ctr_multipart:16:8
+
+AES-CTR aes_encrypt_ctr_multipart 16 15
+aes_encrypt_ctr_multipart:16:15
+
+AES-CTR aes_encrypt_ctr_multipart 16 16
+aes_encrypt_ctr_multipart:16:16
+
+AES-CTR aes_encrypt_ctr_multipart 17 1
+aes_encrypt_ctr_multipart:17:1
+
+AES-CTR aes_encrypt_ctr_multipart 17 2
+aes_encrypt_ctr_multipart:17:2
+
+AES-CTR aes_encrypt_ctr_multipart 17 8
+aes_encrypt_ctr_multipart:17:8
+
+AES-CTR aes_encrypt_ctr_multipart 17 15
+aes_encrypt_ctr_multipart:17:15
+
+AES-CTR aes_encrypt_ctr_multipart 17 16
+aes_encrypt_ctr_multipart:17:16
+
+AES-CTR aes_encrypt_ctr_multipart 63 1
+aes_encrypt_ctr_multipart:63:1
+
+AES-CTR aes_encrypt_ctr_multipart 63 2
+aes_encrypt_ctr_multipart:63:2
+
+AES-CTR aes_encrypt_ctr_multipart 63 8
+aes_encrypt_ctr_multipart:63:8
+
+AES-CTR aes_encrypt_ctr_multipart 63 15
+aes_encrypt_ctr_multipart:63:15
+
+AES-CTR aes_encrypt_ctr_multipart 63 16
+aes_encrypt_ctr_multipart:63:16
+
+AES-CTR aes_encrypt_ctr_multipart 63 17
+aes_encrypt_ctr_multipart:63:17
+
+AES-CTR aes_encrypt_ctr_multipart 64 1
+aes_encrypt_ctr_multipart:64:1
+
+AES-CTR aes_encrypt_ctr_multipart 64 2
+aes_encrypt_ctr_multipart:64:2
+
+AES-CTR aes_encrypt_ctr_multipart 64 8
+aes_encrypt_ctr_multipart:64:8
+
+AES-CTR aes_encrypt_ctr_multipart 64 15
+aes_encrypt_ctr_multipart:64:15
+
+AES-CTR aes_encrypt_ctr_multipart 64 16
+aes_encrypt_ctr_multipart:64:16
+
+AES-CTR aes_encrypt_ctr_multipart 64 17
+aes_encrypt_ctr_multipart:64:17
+
+AES-CTR aes_encrypt_ctr_multipart 1024 1
+aes_encrypt_ctr_multipart:1024:1
+
+AES-CTR aes_encrypt_ctr_multipart 1024 10
+aes_encrypt_ctr_multipart:1024:10
+
+AES-CTR aes_encrypt_ctr_multipart 1024 15
+aes_encrypt_ctr_multipart:1024:15
+
+AES-CTR aes_encrypt_ctr_multipart 1024 16
+aes_encrypt_ctr_multipart:1024:16
+
+AES-CTR aes_encrypt_ctr_multipart 1024 63
+aes_encrypt_ctr_multipart:1024:63
+
+AES-CTR aes_encrypt_ctr_multipart 1024 64
+aes_encrypt_ctr_multipart:1024:64
+
+AES-CTR aes_encrypt_ctr_multipart 1024 65
+aes_encrypt_ctr_multipart:1024:65
+
+AES-CTR aes_encrypt_ctr_multipart 1024 1023
+aes_encrypt_ctr_multipart:1024:1023
+
+AES-CTR aes_encrypt_ctr_multipart 1024 1024
+aes_encrypt_ctr_multipart:1024:1024
diff --git a/tests/suites/test_suite_aes.function b/tests/suites/test_suite_aes.function
index 2ca3f7f..f4950a0 100644
--- a/tests/suites/test_suite_aes.function
+++ b/tests/suites/test_suite_aes.function
@@ -88,6 +88,78 @@
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:MBEDTLS_CIPHER_MODE_CTR */
+void aes_encrypt_ctr_multipart(int length, int step_size)
+{
+    unsigned char key[16];
+    unsigned char ctr_a[16];
+    unsigned char ctr_b[16];
+    unsigned char stream_block_a[16];
+    unsigned char stream_block_b[16];
+    unsigned char *input = NULL;
+    unsigned char *output_a = NULL;
+    unsigned char *output_b = NULL;
+    mbedtls_aes_context ctx;
+    size_t nc_off_a, nc_off_b;
+
+    TEST_ASSERT(length >= 0);
+    TEST_ASSERT(step_size > 0);
+
+    TEST_CALLOC(input, length);
+    TEST_CALLOC(output_a, length);
+    TEST_CALLOC(output_b, length);
+
+    // set up a random key
+    mbedtls_test_rnd_std_rand(NULL, key, sizeof(key));
+
+    // random input
+    mbedtls_test_rnd_std_rand(NULL, input, sizeof(input));
+
+
+    // complete encryption in one call
+    mbedtls_aes_init(&ctx);
+    TEST_ASSERT(mbedtls_aes_setkey_enc(&ctx, key, sizeof(key) * 8) == 0);
+    memset(ctr_a, 0, sizeof(ctr_a));
+    memset(stream_block_a, 0, sizeof(stream_block_a));
+    nc_off_a = 0;
+    TEST_EQUAL(mbedtls_aes_crypt_ctr(&ctx, length, &nc_off_a, ctr_a,
+                                     stream_block_a, input, output_a), 0);
+    mbedtls_aes_free(&ctx);
+
+
+    // encrypt in multiple steps of varying size
+    mbedtls_aes_init(&ctx);
+    TEST_ASSERT(mbedtls_aes_setkey_enc(&ctx, key, sizeof(key) * 8) == 0);
+    memset(ctr_b, 0, sizeof(ctr_b));
+    memset(stream_block_b, 0, sizeof(stream_block_b));
+    nc_off_b = 0;
+    size_t remaining = length;
+    unsigned char *ip = input, *op = output_b;
+    while (remaining != 0) {
+        size_t l = MIN(remaining, (size_t) step_size);
+        step_size *= 2;
+        remaining -= l;
+        TEST_EQUAL(mbedtls_aes_crypt_ctr(&ctx, l, &nc_off_b, ctr_b, stream_block_b, ip, op), 0);
+        ip += l;
+        op += l;
+    }
+
+    // finally, validate that multiple steps produced same result as single-pass
+    TEST_MEMORY_COMPARE(output_a, length, output_b, length);
+    TEST_MEMORY_COMPARE(ctr_a, sizeof(ctr_a), ctr_b, sizeof(ctr_b));
+    TEST_MEMORY_COMPARE(stream_block_a, sizeof(stream_block_a),
+                        stream_block_b, sizeof(stream_block_b));
+    TEST_EQUAL(nc_off_a, nc_off_b);
+
+exit:
+    mbedtls_free(input);
+    mbedtls_free(output_a);
+    mbedtls_free(output_b);
+
+    mbedtls_aes_free(&ctx);
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:!MBEDTLS_BLOCK_CIPHER_NO_DECRYPT */
 void aes_decrypt_ecb(data_t *key_str, data_t *src_str,
                      data_t *dst, int setkey_result)