"The Hills" star Heidi Montag has filed for divorce from her estranged husband Spencer Pratt.
 
Montag walked out on her former reality TV co-star in May and filed for legal separation in June.
 
She has now moved to make the marriage split official after lodging a divorce petition in Santa Monica, California Superior Court on Friday, citing irreconcilable differences.
 
Montag's lawyer, Jodeane Farrell, confirms to People.com: "Heidi has amended her petition for separation and today has filed a petition for dissolution of marriage from Spencer Pratt. The couple has agreed they would like their divorce to be finalized in a timely manner in an out-of-court settlement. Both parties are amicable with each other and over the possibility of finalizing their divorce."
 
Montag and Pratt wed in Mexico in 2008 and exchanged vows for a second time on TV in 2009 amid claims their initial nuptials were not legal and were part of an elaborate publicity stunt.

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