diff --git a/tests/suites/test_suite_bignum_mod.data b/tests/suites/test_suite_bignum_mod.data
new file mode 100644
index 0000000..c76dad8
--- /dev/null
+++ b/tests/suites/test_suite_bignum_mod.data
@@ -0,0 +1,86 @@
+Test mbedtls_mpi_mod_setup #1 (Both representations invalid)
+mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_INVALID:MBEDTLS_MPI_MOD_REP_INVALID:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+Test mbedtls_mpi_mod_setup #2 (Internal representation invalid)
+mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_LE:MBEDTLS_MPI_MOD_REP_INVALID:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+Test mbedtls_mpi_mod_setup #3 (Internal representation invalid)
+mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_BE:MBEDTLS_MPI_MOD_REP_INVALID:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+Test mbedtls_mpi_mod_setup #4 (External representation invalid)
+mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_INVALID:MBEDTLS_MPI_MOD_REP_MONTGOMERY:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+Test mbedtls_mpi_mod_setup #5 (External representation invalid)
+mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_INVALID:MBEDTLS_MPI_MOD_REP_OPT_RED:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
+
+Test mbedtls_mpi_mod_setup #6 (Both representations valid)
+mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_BE:MBEDTLS_MPI_MOD_REP_OPT_RED:0
+
+Test mbedtls_mpi_mod_setup #7 (Both representations valid)
+mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_BE:MBEDTLS_MPI_MOD_REP_MONTGOMERY:0
+
+Test mbedtls_mpi_mod_setup #8 (Both representations valid)
+mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_LE:MBEDTLS_MPI_MOD_REP_OPT_RED:0
+
+Test mbedtls_mpi_mod_setup #9 (Both representations valid)
+mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_LE:MBEDTLS_MPI_MOD_REP_MONTGOMERY:0
+
+Base test mbedtls_mpi_mod_mpi #1
+mpi_mod_mpi:"3e8":"d":"c":0
+
+Base test mbedtls_mpi_mod_mpi #2 (Divide by zero (null))
+mpi_mod_mpi:"3e8":"":"0":MBEDTLS_ERR_MPI_DIVISION_BY_ZERO
+
+Base test mbedtls_mpi_mod_mpi #2 (Divide by zero (1 limb))
+mpi_mod_mpi:"3e8":"0":"0":MBEDTLS_ERR_MPI_DIVISION_BY_ZERO
+
+Base test mbedtls_mpi_mod_mpi #3
+mpi_mod_mpi:"-3e8":"d":"1":0
+
+Base test mbedtls_mpi_mod_mpi #4 (Negative modulo)
+mpi_mod_mpi:"3e8":"-d":"-1":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+Base test mbedtls_mpi_mod_mpi #5 (Negative modulo)
+mpi_mod_mpi:"-3e8":"-d":"-c":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+Test mbedtls_mpi_mod_mpi: 0 (null) % 1
+mpi_mod_mpi:"":"1":"":0
+
+Test mbedtls_mpi_mod_mpi: 0 (null) % -1
+mpi_mod_mpi:"":"-1":"":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+Base test mbedtls_mpi_mod_int #1
+mpi_mod_int:"3e8":13:12:0
+
+Base test mbedtls_mpi_mod_int #2 (Divide by zero)
+mpi_mod_int:"3e8":0:0:MBEDTLS_ERR_MPI_DIVISION_BY_ZERO
+
+Base test mbedtls_mpi_mod_int #3
+mpi_mod_int:"-3e8":13:1:0
+
+Base test mbedtls_mpi_mod_int #4 (Negative modulo)
+mpi_mod_int:"3e8":-13:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+Base test mbedtls_mpi_mod_int #5 (Negative modulo)
+mpi_mod_int:"-3e8":-13:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+Base test mbedtls_mpi_mod_int #6 (By 1)
+mpi_mod_int:"3e8":1:0:0
+
+Base test mbedtls_mpi_mod_int #7 (By 2)
+mpi_mod_int:"3e9":2:1:0
+
+Base test mbedtls_mpi_mod_int #8 (By 2)
+mpi_mod_int:"3e8":2:0:0
+
+Test mbedtls_mpi_mod_int: 0 (null) % 1
+mpi_mod_int:"":1:0:0
+
+Test mbedtls_mpi_mod_int: 0 (null) % 2
+mpi_mod_int:"":2:0:0
+
+Test mbedtls_mpi_mod_int: 0 (null) % -1
+mpi_mod_int:"":-1:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+Test mbedtls_mpi_mod_int: 0 (null) % -2
+mpi_mod_int:"":-2:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
diff --git a/tests/suites/test_suite_bignum_mod.function b/tests/suites/test_suite_bignum_mod.function
new file mode 100644
index 0000000..1543623
--- /dev/null
+++ b/tests/suites/test_suite_bignum_mod.function
@@ -0,0 +1,100 @@
+/* BEGIN_HEADER */
+#include "mbedtls/bignum.h"
+#include "mbedtls/entropy.h"
+#include "bignum_mod.h"
+#include "constant_time_internal.h"
+#include "test/constant_flow.h"
+
+/* Check the validity of the sign bit in an MPI object. Reject representations
+ * that are not supported by the rest of the library and indicate a bug when
+ * constructing the value. */
+static int sign_is_valid( const mbedtls_mpi *X )
+{
+    if( X->s != 1 && X->s != -1 )
+        return( 0 ); // invalid sign bit, e.g. 0
+    if( mbedtls_mpi_bitlen( X ) == 0 && X->s != 1 )
+        return( 0 ); // negative zero
+    return( 1 );
+}
+
+/* END_HEADER */
+
+/* BEGIN_DEPENDENCIES
+ * depends_on:MBEDTLS_BIGNUM_C
+ * END_DEPENDENCIES
+ */
+
+/* BEGIN_CASE */
+void mpi_mod_setup( int ext_rep, int int_rep, int iret )
+{
+    #define MLIMBS 8
+    mbedtls_mpi_uint mp[MLIMBS];
+    mbedtls_mpi_mod_modulus m;
+    int ret;
+
+    memset( mp, 0xFF, sizeof(mp) );
+
+    mbedtls_mpi_mod_modulus_init( &m );
+    ret = mbedtls_mpi_mod_modulus_setup( &m, mp, MLIMBS, ext_rep, int_rep );
+    TEST_EQUAL( ret, iret );
+
+    /* Address sanitiser should catch if we try to free mp */
+    mbedtls_mpi_mod_modulus_free( &m );
+
+    /* Make sure that the modulus doesn't have reference to mp anymore */
+    TEST_ASSERT( m.p != mp );
+
+exit:
+    /* It should be safe to call an mbedtls free several times */
+    mbedtls_mpi_mod_modulus_free( &m );
+
+    #undef MLIMBS
+}
+/* END_CASE */
+
+
+/* BEGIN_CASE */
+void mpi_mod_mpi( char * input_X, char * input_Y,
+                  char * input_A, int div_result )
+{
+    mbedtls_mpi X, Y, A;
+    int res;
+    mbedtls_mpi_init( &X ); mbedtls_mpi_init( &Y ); mbedtls_mpi_init( &A );
+
+    TEST_ASSERT( mbedtls_test_read_mpi( &X, input_X ) == 0 );
+    TEST_ASSERT( mbedtls_test_read_mpi( &Y, input_Y ) == 0 );
+    TEST_ASSERT( mbedtls_test_read_mpi( &A, input_A ) == 0 );
+    res = mbedtls_mpi_mod_mpi( &X, &X, &Y );
+    TEST_ASSERT( res == div_result );
+    if( res == 0 )
+    {
+        TEST_ASSERT( sign_is_valid( &X ) );
+        TEST_ASSERT( mbedtls_mpi_cmp_mpi( &X, &A ) == 0 );
+    }
+
+exit:
+    mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &A );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void mpi_mod_int( char * input_X, int input_Y,
+                  int input_A, int div_result )
+{
+    mbedtls_mpi X;
+    int res;
+    mbedtls_mpi_uint r;
+    mbedtls_mpi_init( &X );
+
+    TEST_ASSERT( mbedtls_test_read_mpi( &X, input_X ) == 0 );
+    res = mbedtls_mpi_mod_int( &r, &X, input_Y );
+    TEST_ASSERT( res == div_result );
+    if( res == 0 )
+    {
+        TEST_ASSERT( r == (mbedtls_mpi_uint) input_A );
+    }
+
+exit:
+    mbedtls_mpi_free( &X );
+}
+/* END_CASE */
diff --git a/tests/suites/test_suite_mpi.data b/tests/suites/test_suite_mpi.data
index f530213..fca6337 100644
--- a/tests/suites/test_suite_mpi.data
+++ b/tests/suites/test_suite_mpi.data
@@ -82,33 +82,6 @@
 Test mpi_write_string #10 (Negative hex with odd number of digits)
 mpi_read_write_string:16:"-1":16:"":3:0:MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL
 
-Test mbedtls_mpi_mod_setup #1 (Both representations invalid)
-mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_INVALID:MBEDTLS_MPI_MOD_REP_INVALID:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
-
-Test mbedtls_mpi_mod_setup #2 (Internal representation invalid)
-mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_LE:MBEDTLS_MPI_MOD_REP_INVALID:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
-
-Test mbedtls_mpi_mod_setup #3 (Internal representation invalid)
-mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_BE:MBEDTLS_MPI_MOD_REP_INVALID:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
-
-Test mbedtls_mpi_mod_setup #4 (External representation invalid)
-mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_INVALID:MBEDTLS_MPI_MOD_REP_MONTGOMERY:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
-
-Test mbedtls_mpi_mod_setup #5 (External representation invalid)
-mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_INVALID:MBEDTLS_MPI_MOD_REP_OPT_RED:MBEDTLS_ERR_MPI_BAD_INPUT_DATA
-
-Test mbedtls_mpi_mod_setup #6 (Both representations valid)
-mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_BE:MBEDTLS_MPI_MOD_REP_OPT_RED:0
-
-Test mbedtls_mpi_mod_setup #7 (Both representations valid)
-mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_BE:MBEDTLS_MPI_MOD_REP_MONTGOMERY:0
-
-Test mbedtls_mpi_mod_setup #8 (Both representations valid)
-mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_LE:MBEDTLS_MPI_MOD_REP_OPT_RED:0
-
-Test mbedtls_mpi_mod_setup #9 (Both representations valid)
-mpi_mod_setup:MBEDTLS_MPI_MOD_EXT_REP_LE:MBEDTLS_MPI_MOD_REP_MONTGOMERY:0
-
 Base test mbedtls_mpi_read_binary #1
 mpi_read_binary:"0941379d00fed1491fe15df284dfde4a142f68aa8d412023195cee66883e6290ffe703f4ea5963bf212713cee46b107c09182b5edcd955adac418bf4918e2889af48e1099d513830cec85c26ac1e158b52620e33ba8692f893efbb2f958b4424":"0941379D00FED1491FE15DF284DFDE4A142F68AA8D412023195CEE66883E6290FFE703F4EA5963BF212713CEE46B107C09182B5EDCD955ADAC418BF4918E2889AF48E1099D513830CEC85C26AC1E158B52620E33BA8692F893EFBB2F958B4424"
 
@@ -1312,66 +1285,6 @@
 Test mbedtls_mpi_div_int: 0 (null) / 1
 mpi_div_int:"":1:"":"":0
 
-Base test mbedtls_mpi_mod_mpi #1
-mpi_mod_mpi:"3e8":"d":"c":0
-
-Base test mbedtls_mpi_mod_mpi #2 (Divide by zero (null))
-mpi_mod_mpi:"3e8":"":"0":MBEDTLS_ERR_MPI_DIVISION_BY_ZERO
-
-Base test mbedtls_mpi_mod_mpi #2 (Divide by zero (1 limb))
-mpi_mod_mpi:"3e8":"0":"0":MBEDTLS_ERR_MPI_DIVISION_BY_ZERO
-
-Base test mbedtls_mpi_mod_mpi #3
-mpi_mod_mpi:"-3e8":"d":"1":0
-
-Base test mbedtls_mpi_mod_mpi #4 (Negative modulo)
-mpi_mod_mpi:"3e8":"-d":"-1":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
-
-Base test mbedtls_mpi_mod_mpi #5 (Negative modulo)
-mpi_mod_mpi:"-3e8":"-d":"-c":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
-
-Test mbedtls_mpi_mod_mpi: 0 (null) % 1
-mpi_mod_mpi:"":"1":"":0
-
-Test mbedtls_mpi_mod_mpi: 0 (null) % -1
-mpi_mod_mpi:"":"-1":"":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
-
-Base test mbedtls_mpi_mod_int #1
-mpi_mod_int:"3e8":13:12:0
-
-Base test mbedtls_mpi_mod_int #2 (Divide by zero)
-mpi_mod_int:"3e8":0:0:MBEDTLS_ERR_MPI_DIVISION_BY_ZERO
-
-Base test mbedtls_mpi_mod_int #3
-mpi_mod_int:"-3e8":13:1:0
-
-Base test mbedtls_mpi_mod_int #4 (Negative modulo)
-mpi_mod_int:"3e8":-13:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
-
-Base test mbedtls_mpi_mod_int #5 (Negative modulo)
-mpi_mod_int:"-3e8":-13:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
-
-Base test mbedtls_mpi_mod_int #6 (By 1)
-mpi_mod_int:"3e8":1:0:0
-
-Base test mbedtls_mpi_mod_int #7 (By 2)
-mpi_mod_int:"3e9":2:1:0
-
-Base test mbedtls_mpi_mod_int #8 (By 2)
-mpi_mod_int:"3e8":2:0:0
-
-Test mbedtls_mpi_mod_int: 0 (null) % 1
-mpi_mod_int:"":1:0:0
-
-Test mbedtls_mpi_mod_int: 0 (null) % 2
-mpi_mod_int:"":2:0:0
-
-Test mbedtls_mpi_mod_int: 0 (null) % -1
-mpi_mod_int:"":-1:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
-
-Test mbedtls_mpi_mod_int: 0 (null) % -2
-mpi_mod_int:"":-2:0:MBEDTLS_ERR_MPI_NEGATIVE_VALUE
-
 Base test mbedtls_mpi_exp_mod #1
 mpi_exp_mod:"17":"d":"1d":"18":0
 
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index ca30d18..c26766b 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -1,7 +1,6 @@
 /* BEGIN_HEADER */
 #include "mbedtls/bignum.h"
 #include "mbedtls/entropy.h"
-#include "bignum_mod.h"
 #include "constant_time_internal.h"
 #include "test/constant_flow.h"
 
@@ -200,34 +199,6 @@
 /* END_CASE */
 
 /* BEGIN_CASE */
-void mpi_mod_setup( int ext_rep, int int_rep, int iret )
-{
-    #define MLIMBS 8
-    mbedtls_mpi_uint mp[MLIMBS];
-    mbedtls_mpi_mod_modulus m;
-    int ret;
-
-    memset( mp, 0xFF, sizeof(mp) );
-
-    mbedtls_mpi_mod_modulus_init( &m );
-    ret = mbedtls_mpi_mod_modulus_setup( &m, mp, MLIMBS, ext_rep, int_rep );
-    TEST_EQUAL( ret, iret );
-
-    /* Address sanitiser should catch if we try to free mp */
-    mbedtls_mpi_mod_modulus_free( &m );
-
-    /* Make sure that the modulus doesn't have reference to mp anymore */
-    TEST_ASSERT( m.p != mp );
-
-exit:
-    /* It should be safe to call an mbedtls free several times */
-    mbedtls_mpi_mod_modulus_free( &m );
-
-    #undef MLIMBS
-}
-/* END_CASE */
-
-/* BEGIN_CASE */
 void mpi_read_binary_le( data_t * buf, char * input_A )
 {
     mbedtls_mpi X;
@@ -1288,52 +1259,6 @@
 /* END_CASE */
 
 /* BEGIN_CASE */
-void mpi_mod_mpi( char * input_X, char * input_Y,
-                  char * input_A, int div_result )
-{
-    mbedtls_mpi X, Y, A;
-    int res;
-    mbedtls_mpi_init( &X ); mbedtls_mpi_init( &Y ); mbedtls_mpi_init( &A );
-
-    TEST_ASSERT( mbedtls_test_read_mpi( &X, input_X ) == 0 );
-    TEST_ASSERT( mbedtls_test_read_mpi( &Y, input_Y ) == 0 );
-    TEST_ASSERT( mbedtls_test_read_mpi( &A, input_A ) == 0 );
-    res = mbedtls_mpi_mod_mpi( &X, &X, &Y );
-    TEST_ASSERT( res == div_result );
-    if( res == 0 )
-    {
-        TEST_ASSERT( sign_is_valid( &X ) );
-        TEST_ASSERT( mbedtls_mpi_cmp_mpi( &X, &A ) == 0 );
-    }
-
-exit:
-    mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &A );
-}
-/* END_CASE */
-
-/* BEGIN_CASE */
-void mpi_mod_int( char * input_X, int input_Y,
-                  int input_A, int div_result )
-{
-    mbedtls_mpi X;
-    int res;
-    mbedtls_mpi_uint r;
-    mbedtls_mpi_init( &X );
-
-    TEST_ASSERT( mbedtls_test_read_mpi( &X, input_X ) == 0 );
-    res = mbedtls_mpi_mod_int( &r, &X, input_Y );
-    TEST_ASSERT( res == div_result );
-    if( res == 0 )
-    {
-        TEST_ASSERT( r == (mbedtls_mpi_uint) input_A );
-    }
-
-exit:
-    mbedtls_mpi_free( &X );
-}
-/* END_CASE */
-
-/* BEGIN_CASE */
 void mpi_exp_mod( char * input_A, char * input_E,
                   char * input_N, char * input_X,
                   int exp_result )