diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index 569ca9e4d..130a9a96c 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -39,19 +39,29 @@
 
 /*
  * Conversion macros for embedded constants:
- * build lists of t_uint's from lists of unsigned char's grouped by 8
+ * build lists of t_uint's from lists of unsigned char's grouped by 8, 4 or 2
  */
 #if defined(POLARSSL_HAVE_INT8)
 
 #define BYTES_TO_T_UINT_8( a, b, c, d, e, f, g, h ) \
     a, b, c, d, e, f, g, h
 
+#define BYTES_TO_T_UINT_4( a, b, c, d )             \
+    a, b, c, d
+
+#define BYTES_TO_T_UINT_2( a, b )                   \
+    a, b
+
 #elif defined(POLARSSL_HAVE_INT16)
 
 #define BYTES_TO_T_UINT_2( a, b )                   \
     ( (t_uint) a << 0 ) |                           \
     ( (t_uint) b << 8 )
 
+#define BYTES_TO_T_UINT_4( a, b, c, d )             \
+    BYTES_TO_T_UINT_2( a, b ),                      \
+    BYTES_TO_T_UINT_2( c, d )
+
 #define BYTES_TO_T_UINT_8( a, b, c, d, e, f, g, h ) \
     BYTES_TO_T_UINT_2( a, b ),                      \
     BYTES_TO_T_UINT_2( c, d ),                      \
@@ -66,6 +76,9 @@
     ( (t_uint) c << 16 ) |                          \
     ( (t_uint) d << 24 )
 
+#define BYTES_TO_T_UINT_2( a, b )                   \
+    BYTES_TO_T_UINT_4( a, b, 0, 0 )
+
 #define BYTES_TO_T_UINT_8( a, b, c, d, e, f, g, h ) \
     BYTES_TO_T_UINT_4( a, b, c, d )                 \
     BYTES_TO_T_UINT_4( e, f, g, h )
@@ -82,8 +95,19 @@
     ( (t_uint) g << 48 ) |                          \
     ( (t_uint) h << 56 )
 
+#define BYTES_TO_T_UINT_4( a, b, c, d )             \
+    BYTES_TO_T_UINT_8( a, b, c, d, 0, 0, 0, 0 )
+
+#define BYTES_TO_T_UINT_2( a, b )                   \
+    BYTES_TO_T_UINT_8( a, b, 0, 0, 0, 0, 0, 0 )
+
 #endif /* bits in t_uint */
 
+/*
+ * Note: the constants are in little-endian order
+ * to be directly usable in MPIs
+ */
+
 /*
  * Domain parameters for secp192r1
  */
@@ -129,25 +153,25 @@ static t_uint secp224r1_b[] = {
     BYTES_TO_T_UINT_8( 0xB4, 0xFF, 0x55, 0x23, 0x43, 0x39, 0x0B, 0x27 ),
     BYTES_TO_T_UINT_8( 0xBA, 0xD8, 0xBF, 0xD7, 0xB7, 0xB0, 0x44, 0x50 ),
     BYTES_TO_T_UINT_8( 0x56, 0x32, 0x41, 0xF5, 0xAB, 0xB3, 0x04, 0x0C ),
-    BYTES_TO_T_UINT_8( 0x85, 0x0A, 0x05, 0xB4, 0x00, 0x00, 0x00, 0x00 ),
+    BYTES_TO_T_UINT_4( 0x85, 0x0A, 0x05, 0xB4 ),
 };
 static t_uint secp224r1_gx[] = {
     BYTES_TO_T_UINT_8( 0x21, 0x1D, 0x5C, 0x11, 0xD6, 0x80, 0x32, 0x34 ),
     BYTES_TO_T_UINT_8( 0x22, 0x11, 0xC2, 0x56, 0xD3, 0xC1, 0x03, 0x4A ),
     BYTES_TO_T_UINT_8( 0xB9, 0x90, 0x13, 0x32, 0x7F, 0xBF, 0xB4, 0x6B ),
-    BYTES_TO_T_UINT_8( 0xBD, 0x0C, 0x0E, 0xB7, 0x00, 0x00, 0x00, 0x00 ),
+    BYTES_TO_T_UINT_4( 0xBD, 0x0C, 0x0E, 0xB7 ),
 };
 static t_uint secp224r1_gy[] = {
     BYTES_TO_T_UINT_8( 0x34, 0x7E, 0x00, 0x85, 0x99, 0x81, 0xD5, 0x44 ),
     BYTES_TO_T_UINT_8( 0x64, 0x47, 0x07, 0x5A, 0xA0, 0x75, 0x43, 0xCD ),
     BYTES_TO_T_UINT_8( 0xE6, 0xDF, 0x22, 0x4C, 0xFB, 0x23, 0xF7, 0xB5 ),
-    BYTES_TO_T_UINT_8( 0x88, 0x63, 0x37, 0xBD, 0x00, 0x00, 0x00, 0x00 ),
+    BYTES_TO_T_UINT_4( 0x88, 0x63, 0x37, 0xBD ),
 };
 static t_uint secp224r1_n[] = {
     BYTES_TO_T_UINT_8( 0x3D, 0x2A, 0x5C, 0x5C, 0x45, 0x29, 0xDD, 0x13 ),
     BYTES_TO_T_UINT_8( 0x3E, 0xF0, 0xB8, 0xE0, 0xA2, 0x16, 0xFF, 0xFF ),
     BYTES_TO_T_UINT_8( 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ),
-    BYTES_TO_T_UINT_8( 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00 ),
+    BYTES_TO_T_UINT_4( 0xFF, 0xFF, 0xFF, 0xFF ),
 };
 #endif /* POLARSSL_ECP_DP_SECP224R1_ENABLED */
 
@@ -246,7 +270,7 @@ static t_uint secp521r1_p[] = {
     BYTES_TO_T_UINT_8( 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ),
     BYTES_TO_T_UINT_8( 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ),
     BYTES_TO_T_UINT_8( 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ),
-    BYTES_TO_T_UINT_8( 0xFF, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ),
+    BYTES_TO_T_UINT_2( 0xFF, 0x01 ),
 };
 static t_uint secp521r1_b[] = {
     BYTES_TO_T_UINT_8( 0x00, 0x3F, 0x50, 0x6B, 0xD4, 0x1F, 0x45, 0xEF ),
@@ -257,7 +281,7 @@ static t_uint secp521r1_b[] = {
     BYTES_TO_T_UINT_8( 0xF3, 0x15, 0xB3, 0x99, 0x5B, 0x72, 0xDA, 0xA2 ),
     BYTES_TO_T_UINT_8( 0xEE, 0x40, 0x85, 0xB6, 0xA0, 0x21, 0x9A, 0x92 ),
     BYTES_TO_T_UINT_8( 0x1F, 0x9A, 0x1C, 0x8E, 0x61, 0xB9, 0x3E, 0x95 ),
-    BYTES_TO_T_UINT_8( 0x51, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ),
+    BYTES_TO_T_UINT_2( 0x51, 0x00 ),
 };
 static t_uint secp521r1_gx[] = {
     BYTES_TO_T_UINT_8( 0x66, 0xBD, 0xE5, 0xC2, 0x31, 0x7E, 0x7E, 0xF9 ),
@@ -268,7 +292,7 @@ static t_uint secp521r1_gx[] = {
     BYTES_TO_T_UINT_8( 0x21, 0xB5, 0x3F, 0x05, 0x39, 0x81, 0x64, 0x9C ),
     BYTES_TO_T_UINT_8( 0x42, 0xB4, 0x95, 0x23, 0x66, 0xCB, 0x3E, 0x9E ),
     BYTES_TO_T_UINT_8( 0xCD, 0xE9, 0x04, 0x04, 0xB7, 0x06, 0x8E, 0x85 ),
-    BYTES_TO_T_UINT_8( 0xC6, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ),
+    BYTES_TO_T_UINT_2( 0xC6, 0x00 ),
 };
 static t_uint secp521r1_gy[] = {
     BYTES_TO_T_UINT_8( 0x50, 0x66, 0xD1, 0x9F, 0x76, 0x94, 0xBE, 0x88 ),
@@ -279,7 +303,7 @@ static t_uint secp521r1_gy[] = {
     BYTES_TO_T_UINT_8( 0x68, 0x44, 0x9B, 0x57, 0x49, 0x44, 0xF5, 0x98 ),
     BYTES_TO_T_UINT_8( 0xD9, 0x1B, 0x7D, 0x2C, 0xB4, 0x5F, 0x8A, 0x5C ),
     BYTES_TO_T_UINT_8( 0x04, 0xC0, 0x3B, 0x9A, 0x78, 0x6A, 0x29, 0x39 ),
-    BYTES_TO_T_UINT_8( 0x18, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ),
+    BYTES_TO_T_UINT_2( 0x18, 0x01 ),
 };
 static t_uint secp521r1_n[] = {
     BYTES_TO_T_UINT_8( 0x09, 0x64, 0x38, 0x91, 0x1E, 0xB7, 0x6F, 0xBB ),
@@ -290,7 +314,7 @@ static t_uint secp521r1_n[] = {
     BYTES_TO_T_UINT_8( 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ),
     BYTES_TO_T_UINT_8( 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ),
     BYTES_TO_T_UINT_8( 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF ),
-    BYTES_TO_T_UINT_8( 0xFF, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ),
+    BYTES_TO_T_UINT_2( 0xFF, 0x01 ),
 };
 #endif /* POLARSSL_ECP_DP_SECP521R1_ENABLED */