Fans are calling out Justin Bieber's ALS ice bucket challenge because it lacked one major ingredient - ice.

The idea is that participants involved in the challenge have 24 hours to either dump a bucket of ice water over their heads or donate to the Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disease also known as Lou Gehrig's disease.

Over the weekend, Bieber became the latest celebrity to take the challenge after being nominated by his manager Scooter Braun. The Canadian singer posted two videos of himself completing the challenge on Sunday, before nominating President Barack Obama, Ellen DeGeneres and all his Beliebers.

However, some fans are crying foul after noticing the singer used only water but no ice in his two attempts at the challenge. His first dumped a small saucepan over his head, instead of a bucket.

Bieber chose to ignore the criticism and retweet several messages from his fans that also completed the challenge and/or donated funds to the foundation.

The ice bucket challenge has become a social media phenomenon, which has been completed by several celebrities including Ben Affleck, Jennifer Lopez, Conan O'Brien, Oprah Winfrey, Steven Spielberg, Justin Timberlake, Selena Gomez, Taylor Swift and Mark Zuckerberg.

As of Saturday, the ALS Association had received $11.4 million in donations compared to $1.7 million in 2013, according to the organization's website.

LOL so both of @justinbieber's ice bucket challenge videos show him pouring water over his head, with no ice... In both videos. ✋