diff --git a/com.oracle.truffle.r.native/fficall/src/truffle_nfi/Rinternals.c b/com.oracle.truffle.r.native/fficall/src/truffle_nfi/Rinternals.c
index 026f9f5ba7ac34fec67bd787262cb9929768d014..db41b21bcca1e7779fd5c89223375ac18c63ccd0 100644
--- a/com.oracle.truffle.r.native/fficall/src/truffle_nfi/Rinternals.c
+++ b/com.oracle.truffle.r.native/fficall/src/truffle_nfi/Rinternals.c
@@ -906,7 +906,7 @@ SEXP *VECTOR_PTR(SEXP x){
 }
 
 SEXP Rf_asChar(SEXP x){
-	return unimplemented("Rf_asChar");
+	return ((call_Rf_asChar) callbacks[Rf_asChar_x])(x);
 }
 
 SEXP Rf_PairToVectorList(SEXP x){
@@ -931,8 +931,7 @@ int Rf_asInteger(SEXP x) {
 }
 
 double Rf_asReal(SEXP x) {
-	unimplemented("Rf_asReal");
-	return 0.0;
+	return ((call_Rf_asReal) callbacks[Rf_asReal_x])(x);
 }
 
 Rcomplex Rf_asComplex(SEXP x){