diff --git a/tests/suites/test_suite_ecp.data b/tests/suites/test_suite_ecp.data
index 15f9094..20ae3cd 100644
--- a/tests/suites/test_suite_ecp.data
+++ b/tests/suites/test_suite_ecp.data
@@ -133,6 +133,18 @@
 ECP small check pubkey #10
 ecp_small_check_pub:10:25:1:POLARSSL_ERR_ECP_GENERIC
 
+ECP write binary #1 (zero, buffer just fits)
+ecp_write_binary:SECP192R1:"01":"01":"00":"00":1:0
+
+ECP write binary #2 (zero, buffer too small)
+ecp_write_binary:SECP192R1:"01":"01":"00":"00":0:POLARSSL_ERR_ECP_GENERIC
+
+ECP write binary #3 (non-zero, buffer just fits)
+ecp_write_binary:SECP192R1:"48d8082a3a1e3112bc03a8ef2f6d40d0a77a6f8e00cc9933":"6ceed4d7cba482e288669ee1b6415626d6f34d28501e060c":"01":"0448d8082a3a1e3112bc03a8ef2f6d40d0a77a6f8e00cc99336ceed4d7cba482e288669ee1b6415626d6f34d28501e060c":49:0
+
+ECP write binary #4 (non-zero, buffer too small)
+ecp_write_binary:SECP192R1:"48d8082a3a1e3112bc03a8ef2f6d40d0a77a6f8e00cc9933":"6ceed4d7cba482e288669ee1b6415626d6f34d28501e060c":"01":"0448d8082a3a1e3112bc03a8ef2f6d40d0a77a6f8e00cc99336ceed4d7cba482e288669ee1b6415626d6f34d28501e060c":48:POLARSSL_ERR_ECP_GENERIC
+
 ECP mod p192 readable
 ecp_fast_mod:SECP192R1:"000000000000010500000000000001040000000000000103000000000000010200000000000001010000000000000100"
 
diff --git a/tests/suites/test_suite_ecp.function b/tests/suites/test_suite_ecp.function
index 0fcc842..1e50499 100644
--- a/tests/suites/test_suite_ecp.function
+++ b/tests/suites/test_suite_ecp.function
@@ -225,6 +225,39 @@
 END_CASE
 
 BEGIN_CASE
+ecp_write_binary:id:x:y:z:out:blen:ret
+{
+    ecp_group grp;
+    ecp_point P;
+    unsigned char buf[256], str[512];
+    size_t olen;
+
+    memset( buf, 0, sizeof( buf ) );
+    memset( str, 0, sizeof( str ) );
+
+    ecp_group_init( &grp ); ecp_point_init( &P );
+
+    TEST_ASSERT( ecp_use_known_dp( &grp, POLARSSL_ECP_DP_{id} ) == 0 );
+
+    TEST_ASSERT( mpi_read_string( &P.X, 16, {x} ) == 0 );
+    TEST_ASSERT( mpi_read_string( &P.Y, 16, {y} ) == 0 );
+    TEST_ASSERT( mpi_read_string( &P.Z, 16, {z} ) == 0 );
+
+    TEST_ASSERT( ecp_write_binary( &grp, &P, &olen, buf, {blen} ) == {ret} );
+
+    if( {ret} == 0 )
+    {
+        TEST_ASSERT( olen == strlen({out}) / 2 );
+
+        hexify( str, buf, {blen} );
+        TEST_ASSERT( strcasecmp( (char *) str, {out} ) == 0 );
+    }
+
+    ecp_group_free( &grp ); ecp_point_free( &P );
+}
+END_CASE
+
+BEGIN_CASE
 ecp_selftest:
 {
     TEST_ASSERT( ecp_self_test( 0 ) == 0 );