delivered the opinion of the court:
The petitioner-appellant, Sherri L. Zuidema (Sherri), appeals from an order of the circuit court of Whiteside County which transferred to the respondent-appellee, Steven J. Zuidema (Steven), custody of the parties’ two minor daughters.
Sherri contends that the trial court abused its discretion in modifying the custodial arrangements of the minor children, and lacked authority to modify custody under section 610(b) of the Illinois Marriage and Dissolution of Marriage Act (IMDMA). For the reasons set forth below, we do not address these contentions.
On December 12, 1975, a decree was entered dissolving the marriage of Sherri and Steven Zuidema. The decree incorporated a written settlement agreement in which the parties stipulated that custody of their minor children would be awarded to Sherri. On May 7, 1982, a hearing was conducted on a petition by Steven to modify the di*851vorce decree. An order was subsequently entered on May 26, 1982, which provided that custody of the minor children would remain with Sherri but would be transferred to Steven if she violated certain conditions.
On June 27, 1983, Steven filed a second petition to modify which alleged that Sherri had violated the conditions imposed by the trial court on May 26, 1982. A hearing was conducted on February 27, 1984, at which time the trial court heard testimony from Sherri, her boyfriend, her mother, and Steven. The court also interviewed the two minor children separately, in camera. On March 8, 1984, the trial court entered an order transferring custody of the two children to Steven. A post-trial motion filed by Sherri was denied by the court.
Modification of custody judgments is governed by section 610 of the IMDMA. (Ill. Rev. Stat. 1981, ch. 40, par. 610.) Section 610 was amended by Public Act 82 — 715, effective July 1, 1982. Thus, the amendment occurred after the trial court’s ruling on Steven’s first petition to modify but prior to the time he filed his second petition to modify. Under section 610, as amended, a different standard is applied in cases such as this depending on whether a motion to modify a custody judgment is made within two years after the judgment was entered.
We have reviewed the record and are unable to determine what standard the trial court applied when it ruled on Steven’s second petition to modify. It is unclear whether the court applied section 610 as it existed prior to its amendment or the terms of section 610 as amended. Furthermore, assuming that the trial court applied section 610 as amended, it is unclear whether it proceeded under subsection (a) or subsection (b). Therefore, we reverse and remand.
For the foregoing reasons, the judgment of the circuit court of Whiteside County is reversed and remanded.
Reversed and remanded.
SCOTT, J., concurs.