diff --git a/library/ecp_invasive.h b/library/ecp_invasive.h
index 19d516f..2669aec 100644
--- a/library/ecp_invasive.h
+++ b/library/ecp_invasive.h
@@ -94,6 +94,13 @@
 
 #endif /* MBEDTLS_ECP_DP_SECP192R1_ENABLED */
 
+#if defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED)
+
+MBEDTLS_STATIC_TESTABLE
+int ecp_mod_p224_raw(mbedtls_mpi_uint *Np, size_t Nn);
+
+#endif /* MBEDTLS_ECP_DP_SECP224R1_ENABLED */
+
 #if defined(MBEDTLS_ECP_DP_SECP521R1_ENABLED)
 
 /** Fast quasi-reduction modulo p521 = 2^521 - 1 (FIPS 186-3 D.2.5)