diff --git a/com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/data/RPromise.java b/com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/data/RPromise.java
index 2f7d1004bdb1df1500e7962bbffcd60e7b433fd8..d00b8e455b51a5c1f9798159a6c029ea78f64191 100644
--- a/com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/data/RPromise.java
+++ b/com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/data/RPromise.java
@@ -204,7 +204,8 @@ public class RPromise implements RTypedValue {
     }
 
     /**
-     * Discards any previously evaluated value if this is not an eager promise.
+     * Discards any previously evaluated value if this is not an eager promise. This is for
+     * debugging purposes only!
      */
     public final void resetValue() {
         // Only non-eager promises can be reset.