Opinion by
Judge Wilkinson, Jr.,Petitioner (claimant) appeals from an order of the Workmen’s Compensation Appeal Board (Board) which reversed an award of compensation made by the referee on the grounds that a compensable injury had not been proven as a matter of law within the meaning of Section 301(c) of The Pennsylvania Workmen’s Compensation Act (Act).1 We affirm.
Claimant is the widow of John Krawchuk, who sustained a fatal myocardial infarction (heart attack) in his home shortly after midnight on May 10, 1973. The decedent, 52 at the time of his death, had been employed by the respondent, Philadelphia Electric Com*594pany, as an electrical engineer for approximately 27 years.
On October 12, 1973, the claimant filed a fatal claim petition alleging the decedent’s heart attack was dne to excessive strain and pressure in connection with his work. At the referee’s hearing, claimant testified that her husband would frequently bring work home from the office and work in his shop in the basement after dinner. She testified that on the night of his death decedent worked for approximately five hours after dinner on a paper which he was to deliver at a public utilities meeting in Los Angeles on May 14, 1973. Claimant also offered the testimony of decedent’s physician who examined the decedent during a routine office visit the day before his death. The decedent told his physician that he was under stress because he was concerned about the paper; the physician then stated that in his opinion there was a causal connection between the stress decedent related to him and his death the next day.
The employer presented nine witnesses, all of whom worked in the same engineering division with the decedent. The engineer in charge of the division testified that in addition to his regularly assigned duties, decedent had been working on a specially assigned project, called PMS4, regarding the potential use of computers in the division. The supervisor testified that decedent was offered the project because of his special interest and experience; that decedent voluntarily undertook the project; that he generally worked alone, although help was available to him; and that no deadline was set on the project. He further stated that decedent was not required to work beyond regular business hours and that he (his supervisor) was not aware that the decedent was working at home. Five other witnesses who either were or had been decedent’s supervisors also testified that decedent had *595not been required to work at home or beyond regular business hours. These witnesses further testified that after decedent returned to work following a non-work related heart attack in 1967 he was given a reduced work load. His immediate supervisor testified that at the time of his death decedent was assigned to complete one substation design with a 1975 deadline.
The referee made the following findings of fact relative to his conclusion that the heart attack constituted a compensable injury:
7. At the time of his death, Claimant’s decedent was working under great and unusual stress stemming from the work he was doing in connection with a special project known as ‘PMS4’, and a treatise he was to deliver, on behalf of his employer, in California. . . .
10. All of the above activities constituted additional and unusual exertion on the part of Claimant’s decedent, arising from and related to his employment.
11. On the day prior to his heart attack, Claimant’s decedent was examined by Dr. Albert Kraft, who at the time found the Claimant’s decedent to appear tired and under great stress due to his added work load.
12. For five hours prior to the heart attack, Claimant’s decedent had been working in his home on the treatise. . . .
13. Dr. Kraft, a cardiology specialist, testified as to a causal relationship between the stress occasioned by Claimant’s decedent’s heavy work load and the coronary which he sustained on May 10, 1973. . . .
*596Therefore, the referee concluded that the decedent
suffered a compensable injury within the meaning of the Act when he sustained a fatal coronary attack at his home after an extended period of additional and unusual strain and exertion, including five hours at home immediately prior to his coronary attack, in carrying on for his employer his duties in a special project at work and in the preparation of the material for a treatise he was to deliver. . . .
On appeal, the Board vacated the referee’s conclusions of law that the decedent had suffered a compensable injury, finding that the referee failed to make a necessary finding of fact that the decedent had been in the course of his employment at the time of his death. After a review of the testimony, the Board concluded that there was insufficient evidence to support such a finding and dismissed the claim.
Before this Court, claimant argues that the Board exceeded its authority in dismissing the claim because the Board’s conclusion that decedent was not in the course of his employment based on the employer’s evidence was tantamount to rejecting a finding of fact made by the referee which found this testimony “not to be persuasive as to the lack of stress . . . especially because they were not familiar with the extent of the work performed by claimant’s decedent at his home . . . and particularly during several hours on the evening immediately preceding his death.”
However, it is clear from a reading of this finding that the referee was referring to the causal relationship between decedent’s death and the stress he experienced from his work, rather than a finding relating to facts that must be established to show that the employee was in the course of his employment at the time of his death. The question of whether an em*597ployee is in tlie course of Ms employment in order to qualify for benefits under the Act is one of law and the referee’s determination on this issue is subject to review and reversal by the Board. Buchan v. Royal Pizza House, Inc., 28 Pa. Commonwealth Ct. 121, 367 A.2d 824 (1977). Further, the burden is upon the claimant to prove that the injury was sustained in the course of employment. J. R. Hess, Inc. v. Workmen’s Compensation Appeal Board, 17 Pa. Commonwealth Ct. 87, 329 A.2d 923 (1975). The only finding of fact made by the referee concerning course of employment is contained in Finding of Fact 10 which is a mere conclusion of law. Therefore, we conclude the Board did not exceed its proper scope of review.2
Turning to the ultimate issue — whether the decedent’s heart attack occurred while he was in the course of his employment — the claimant argues her testimony concerning the decedent’s work habits at home is sufficient to establish the requisite facts to show that the decedent died while in the course of his employment.
*598When an employee is injured off the premises of his employer, the injury is deemed to have arisen in the course of employment only if it is shown that the employee is actually engaged in the furtherance of the employer’s business. Cozza v. Workmen’s Compensation Appeal Board, 34 Pa. Commonwealth Ct. 605, 383 A.2d 1324 (1978). Where an employee is injured in his home, furtherance of the employer’s business has been held to mean that the employee was doing something at home for the convenience of his employer, that he was performing a specific duty by reason of a clearcut request by his employer or that the employer directed the employee to work at home. See LoPresti v. Workmen’s Compensation Appeal Board, 35 Pa. Commonwealth Ct. 7, 384 A.2d 1017 (1978); Workmen’s Compensation Appeal Board v. Hickory Farms, 28 Pa. Commonwealth Ct. 30, 367 A.2d 730 (1976). Thus, an employee who chooses to work at home, for whatever reasons personal to him, and not at the behest of his employer, is doing so for his own convenience rather than that of his employer.
Here, the findings of the referee, as established by the evidence support the conclusion that the decedent was extremely interested in the special “PMS4” project and that he worked on the paper which dealt with this project at home in the evenings. The record, however, is devoid of any evidence that the decedent was under a deadline or told to complete the paper even if this meant working beyond normal business hours. The claimant’s testimony and that of decedent’s physician established only that the decedent himself was anxious to complete the paper and wished to do a good job on it. On the other hand, the uncontradicted evidence of the employer established that the decedent’s hours of employment were definitely fixed; that no immediate deadline had been set on decedent’s work; and that the decedent’s supervisors did not re*599quest and were unaware that the decedent worked at home. Indeed, the referee’s finding of fact referred to earlier supports the conclusion that the referee found this testimony credible. It is axiomatic that one cannot acquiesce in what one does not know. See Titus v. S. E. Sostmann & Co., 133 Pa. Superior Ct. 201, 2 A.2d 580 (1938). Given such evidence and in light of this finding made by the referee, we must agree with the Board that the referee erred as a matter of law in finding that the decedent’s heart attack arose in the course of his employment.
Accordingly, we will enter the following
Order
And Now, February 26, 1979, the order of the Workmen’s Compensation Appeal Board, at No. A-72689, dated July 21, 1977, is hereby affirmed.
Act of June 2, 1915, P.L. 736, as amended, 77 P.S. §411. This Section reads in relevant part:
The terms ‘injury’ and ‘personal injury’ as used in this act, shall be construed to mean an injury to an employe . . . arising in the course of his employment and related thereto. .. . The term ‘injury arising in the course of employment,’ as used in this article . . . shall include all . . . injuries sustained while the employe is actually engaged in the furtherance of the business or affairs of his employer whether upon the employer’s premises or elsewhere. . . .
See Section 424 of tlie Act, 77 P.S. §855.
It is true, as claimant suggests, that the causal relationship between the death of the decedent and the stress of his work was established by medical testimony which was accepted by the referee and is therefore binding on the Board and this Court. However, in order to sustain a finding of a compensable injury pursuant to Section 301(c) the claimant must adduce evidence sufficient to establish first, a causal connection between the injury and employment and second, that the injury or death arose in the course of employment. It is the latter element or requirement upon which the Board based its decision and to which our attention is directed. Consequently, .those decisions upon which the claimant relies for the general proposition that heart attacks are compensable injuries are inapplicable since those cases concerned the issue of whether or not a causal connection had been established relating to an injury that unquestionably arose in the course of employment. See, e.g., City of Johnstown v. Workmen’s Compensation Appeal Board, 33 Pa. Commonwealth Ct. 464, 381 A.2d 1355 (1978).