The availability of sloppy interpretation for null arguments differs across languages. This difference is a challenge for child learners because they are unlikely to receive sufficient input that provides clear evidence about the available interpretation. Theories suggest that knowing the presence/absence of agreement could help solving this learning problem. While languages like Japanese that lack agreement allow argument ellipsis (hence the sloppy reading is available), languages with a rich agreement system like Spanish do not. This study explores the utility of this correlation as a cue for learners to infer the available interpretation of a null argument. We show that Japanese adults who learned semi-artificial Japanese that has object-verb agreement are more likely to accept the strict reading than the ones who learned only an artificial singular/plural marker attached to an object. Our results provide evidence that agreement may play a role in learning the interpretation of null arguments.