diff --git a/library/ecp.c b/library/ecp.c
index 049a1e0..29f5bc7 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -3639,7 +3639,7 @@
 #if defined(MBEDTLS_TEST_HOOKS)
 
 MBEDTLS_STATIC_TESTABLE
-mbedtls_ecp_variant mbedtls_ecp_get_variant()
+mbedtls_ecp_variant mbedtls_ecp_get_variant(void)
 {
     return MBEDTLS_ECP_VARIANT_WITH_MPI_STRUCT;
 }