diff --git a/library/ecp_invasive.h b/library/ecp_invasive.h
index 3d1321c..10aa34b 100644
--- a/library/ecp_invasive.h
+++ b/library/ecp_invasive.h
@@ -28,6 +28,7 @@
 
 #include "common.h"
 #include "mbedtls/bignum.h"
+#include "bignum_mod.h"
 #include "mbedtls/ecp.h"
 
 #if defined(MBEDTLS_TEST_HOOKS) && defined(MBEDTLS_ECP_C)
@@ -117,6 +118,11 @@
 
 #endif /* MBEDTLS_ECP_DP_SECP521R1_ENABLED */
 
+MBEDTLS_STATIC_TESTABLE
+int mbedtls_ecp_modulus_setup(mbedtls_mpi_mod_modulus *N,
+                              const mbedtls_ecp_group_id id,
+                              const mbedtls_ecp_curve_type ctype);
+
 #endif /* MBEDTLS_TEST_HOOKS && MBEDTLS_ECP_C */
 
 #endif /* MBEDTLS_ECP_INVASIVE_H */