Five-time Grand Slam champion Iga Swiatek accepted a one-month suspension after testing positive for the banned substance trimetazidine, a heart medication known as TMZ, the International Tennis Integrity Agency announced Thursday.

Swiatek failed an out-of-competition drug test in August, and the ITIA accepted her explanation that the result was unintentional and was caused by the contamination of a nonprescription medication, melatonin, that Swiatek was taking for issues with jet lag and sleeping.

It was determined her level of fault was “at the lowest end of the range for no significant fault or negligence,” the IATA said.

Swiatek is a 23-year-old from Poland who was ranked No. 1 most of the past two seasons but is now at No. 2. She won the French Open in June for her fifth major championship and took home a bronze medal at the Paris Olympics in early August.