diff --git a/ChangeLog.d/add-missing-parenthesis.txt b/ChangeLog.d/add-missing-parenthesis.txt
new file mode 100644
index 000000000..9576ff379
--- /dev/null
+++ b/ChangeLog.d/add-missing-parenthesis.txt
@@ -0,0 +1,3 @@
+Bugfix
+   * Fix a compilation error when MBEDTLS_ECP_RANDOMIZE_MXZ_ALT is
+     defined. Fixes #4217.
diff --git a/library/ecp.c b/library/ecp.c
index fe41b4128..2168981af 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2505,7 +2505,7 @@ static int ecp_randomize_mxz( const mbedtls_ecp_group *grp, mbedtls_ecp_point *P
 
 #if defined(MBEDTLS_ECP_RANDOMIZE_MXZ_ALT)
     if( mbedtls_internal_ecp_grp_capable( grp ) )
-        return( mbedtls_internal_ecp_randomize_mxz( grp, P, f_rng, p_rng );
+        return( mbedtls_internal_ecp_randomize_mxz( grp, P, f_rng, p_rng ) );
 #endif /* MBEDTLS_ECP_RANDOMIZE_MXZ_ALT */
 
     p_size = ( grp->pbits + 7 ) / 8;