diff --git a/com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/RDeparse.java b/com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/RDeparse.java
index a7860653075d8897e8378464797924b158d3d477..1e71eb1a4648005dcd831ada20bfa44ff61a728f 100644
--- a/com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/RDeparse.java
+++ b/com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/RDeparse.java
@@ -745,6 +745,9 @@ public class RDeparse {
                         }
                         needsParens = mainOp.prec > arginfo.prec || (mainOp.prec == arginfo.prec && isLeft == mainOp.rightassoc);
                         break;
+                    case FUNCTION:
+                        needsParens = true;
+                        break;
                     default:
                         break;
                 }