Opinion by
Judge MacPhail,Arcadia Coal Company (Employer) appeals from a decision by the Workmen’s Compensation Appeal Board (Board) which affirmed the referee’s award of compensation benefits to Joseph Kubalic (Claimant).
Claimant worked as a coal miner for Employer for seven years. Claimant terminated his employment on October 15, 1976, because his shortness of wind made *150it impossible for bim to perform bis coal mining work. On April 3,1979, Claimant was examined by Dr. Robert F. Klemens wbo diagnosed Claimant’s condition as coal worker’s pneumoconiosis. Dr. Klemens mailed bis report wbiob contained bis diagnosis to Claimant on or about April 9,1979.
Tbe controversy in tbe case sub judice concerns tbe issue of Claimant’s knowledge of bis disability. On direct examination, Claimant testified tbat be did not know about tbe contents of tbe report until it was explained to bim at bis attorney’s office on May 1,1980. On cross-examination, Claimant testified tbat be received Dr. Klemens’ report sometime in April 1979, and tbat on tbe day of bis examination, Dr. Klemens told Claimant tbat be bad coal worker’s pneumoconiosis from inbaling coal dust at work which caused Claimant to be disabled.1 Dr. Klemens testified tbat *151be bad no recollection of discussing tbe results of tbe examination with Claimant.2
Claimant filed a claim petition for compensation benefits on May 9, 1980. Tbe referee found, based on Dr. Siemens’ medical report and testimony, tbat Claimant was partially disabled from coal workers’ pneumoconiosis as of April 3, 1979; and tbat Claimant first knew of bis disability on May 1, 1980. Tbe Board affirmed tbe referee’s decision.
Employer argues tbat tbe referee’s fact-finding tbat Claimant first knew of bis disability on May 1, 1980, is unsupported by substantial evidence, and tbat tbe referee erred in failing to make a finding as to wben tbe Claimant should bave known by tbe exercise of reasonable diligence of tbe existence of tbe disability.
It is well settled tbat timeliness of a claimant’s notice of bis disability to bis employer is mandatory *152for recovery of workmen’s compensation benefits. Duquesne Light Co. v. Workmen’s Compensation Appeal Board, 53 Pa. Commonwealth Ct. 92, 95, 416 A.2d 651, 653 (1980). Section 311 of The Pennsylvania Workmen’s Compensation Act, Act of June 2, 1915, P.L. 736, as amended, 77 P.S. §631, ,sets forth the specific time limitation for giving notice to the employer.
Unless the employer shall have knowledge of the occurrence of the injury, or unless the employe or someone in his behalf, or some of the dependents or someone in their behalf, shall give notice thereof to the employer within the twenty-one days after the injury, no compensation shall be due until such notice be given and, unless such notice be given within one hundred and twenty days after the occurrence of the injury, no compensation shall be allowed. However, in cases of injury resulting from ionizing radiation or any other cause in which the nature of the injury or its relationship to the employment is not known to the employe, the time for giving notice shall not begin to run until the employe knows, or by the exercise of reasonable diligence should know, of the existence of the injury and its possible relationship to his employment. (Emphasis added.)
This Court has held that for purposes of this section, computing the 120 day time limit for giving notice of an occupational disease runs from the date that a claimant 1) is disabled and 2) knows or should know through the exercise of reasonable diligence of the possible relationship between the disability and his employment. McManus v. Rochester and Pittsburgh Coal Co., 29 Pa. Commonwealth Ct. 91, 94, 368 A.2d 1365, 1367 (1977).
Though the referee in the case sub judice made the finding of fact that Claimant first knew of his dis*153ability on May 1,1980, the referee did not make a finding of when Claimant should have known by exercise of reasonable diligence of Claimant’s disability and its relationship to Claimant’s employment. When there is evidence in the record that Claimant, if he had exercised reasonable diligence, may have acquired such knowledge from which a referee could find that Claimant should have known of his disability from an occupational disease and its causal relationship to his employment, a finding by the referee of when Claimant should have known these matters is necessary for our review. Duquesne, 53 Pa. Commonwealth Ct. at 97, 416 A.2d at 654.
Our review of the record reveals that there is evidence from which the referee could find that Claimant should have known about his disability prior to May 1, 1980. Claimant testified that in April 1979, he received Dr. Siemens’ report and that Doctor Siemens told him at the time of the examination that Claimant was unable to work because he had coal dust in his lungs.3 When a referee fails to make a proper fact-finding, the reviewing Court must remand the case so that the error can be cured. Scranton Garment Co. v. Workmen’s Compensation Appeal Board, 33 Pa. Commonwealth Ct. 190, 194, 381 A.2d 210, 212 (1977). We remand so that the referee can make the proper fact-finding regarding whether the Claimant should have known of his disability from an occupational disease which was causally related to his employment prior to May 1, 1980.
Obder
We vacate the decision of the Workmen’s Compensation Appeal Board dated March 18, 1982, at No. A-81575 and remand for proceedings consistent with this opinion. Jurisdiction is relinquished.
Claimant testified on cross-examination:
Q: ¡Now, after Dr. Klemens examined you on April 3rd, 1979, he prepared this report dated April 9, 1979; is that right?
A: Yeah.
Q: Did he forward that report to your home?
A: Yeah.
Q: Would that have been sometime around April of 1979?
A: Somewhere around that time.
Q: So you received Dr. Klemens’s report dated April 9th, 1979 sometime in April of 1979?
A: Yes.
Q: When Dr. Klemens’s examined you did he tell you that you had dust in your lungs?
A: Yes.
Q: So you knew then in 1979 that you had coal workers’ pneumoconiosis and that it was causing sufficient disability that you were not able to perform the types of work you had performed in the past; is that correct?
A: Yes.
*151Q: Now this disability from pneumoconiosis that Dr. Klemens advised you about, did you attribute this pneumoconiosis and black lung to your coal mining work?
A: Yes.
Dr. Klemens testified:
Q : Did you only see Mr. Kubalic on one occasion?
A: To my knowledge, yes.
Q: Is it possible that you talked to Mr. Kubalic on the telephone following your examination? ■
A: That’s a possibility. Occasionally individuals will call and ask me about the report. But, you know, I have no notation that I did that, nor do I remember doing that.
Q: Doctor, Mr. Kubalic has indicated that you advised him of the results of the examination. He really wasn’t specific as to when you 'advised him of those results. Can you state with a reasonable degree of medical certainty that you never discussed the results of the exam with Mr. Kubalic whether it be by telephone or some other means?
A: That’s my thoughts. Now, ‘there is 'an outside chance that we did discuss it on the telephone. I wouldn’t swear that I didn’t, but I have no recollection that’s what happened.
See supra note 1.