delivered the opinion of the court:
Defendant Richard E. Hills appeals from an order of the Circuit Court of Knox County revoking his probation and sentencing him to a term of two to six years in the penitentiary. Four errors assigned by defendant are: (1) that his confession was improperly admitted into evidence; (2) that he was denied effective assistance of counsel; (3) that his sentence was modified illegally eight days after imposition; (4) that the sentence was excessive.
Defendant was originally charged with possession of a controlled substance with intent to deliver after police intercepted a letter in which had been placed .2 grams of a white powder containing a drug known as MDA. The letter had been mailed by defendant to Michael Eades, a prison inmate at Vandalia, Illinois. After defendant pleaded guilty to the charge, he was sentenced to two years probation beginning January 5, 1976. In April of 1977, a petition to revoke defendant’s probation was filed in Knox County alleging in count I that defendant committed a burglary of the London Mills Recreation Center on March 10,1977, and in count II that he committed an attempt burglary of the London Mills Drug Store on March 14, 1977. Charges of burglary and attempt burglary had previously been filed against defendant in Fulton County where both crimes were allegedly committed. On April 12, 1977, the Circuit Court of Knox County appointed the public defender to represent defendant in the revocation proceedings.
At the probation revocation hearing on May 19, the public defender asked for a continuance and stated that he felt he could not adequately prepare a defense because he had not yet discussed the case with defendant. Counsel explained that after his appointment, defendant called to say that private counsel had been retained. When the public defender contacted the named attorney, he learned that private counsel would not represent defendant in Knox County but only in the Fulton County proceedings. By that time defendant was out on bond, and the public defender was unable to reach him to discuss the case. The State objected to the continuance because defendant was negligent in failing to contact the public defender after he knew that private counsel was not available and also because the State’s witnesses from Fulton County were present in the courtroom. The court denied the continuance, and both parties then agreed to proceed with testimony from the State’s witnesses who were present and to continue the case for the defense to a later date.
The State’s witnesses testified that on the morning of March 10, the owners of the London Mills Recreation Center, which included a restaurant and pool hall, discovered that the Center had been broken into during the night and that items having a value of *200 to *250 were missing.
*464Among the stolen items were several pool cues, some boxes of candy bars, gum and cigarettes, and *90 in change. The thieves had entered by breaking a padlock on the door of an adjoining garage and then breaking through a connecting wooden door into the Center.
Gary Phillips, a criminal investigator with the Illinois State Police, testified that about 2 p.m. on the afternoon of March 14, he talked to defendant in the presence of another State policeman and the Fulton County State’s Attorney and obtained a statement from defendant concerning the March 10 burglary at the Recreation Center in London Mills. According to this statement, defendant and two friends had been drinking beer and while driving through London Mills, they decided to break into the Center. One friend had passed out in the back seat of the car, so defendant and the other friend, Melvin Thomas, used a crowbar from the trunk of defendant’s car to break the padlock on the garage door and to take the hinges off the connecting door. Once inside the Center, they helped themselves to five or six pool cues, cigarettes, gum and some change, all of which they took to the friend’s apartment.
Defense counsel objected to the admission into evidence of defendant’s statement on the ground that defendant was “laboring under the difficulty of intoxication,” but the court denied the objection. According to previously adduced evidence, the statement was taken some 12 hours after defendant’s arrest and thus 12 hours after the use of any intoxicants. Officer Phillips testified that defendant appeared to be sober but very tired at the time he gave the statement.
The State then rested its case as to count I and proceeded to introduce evidence concerning count II of the Revocation petition.
Walter R. Riley testified that about 1 a.m. on the morning of March 14, he was awakened by a loud noise. He got up and looked out the window of his upstairs apartment but saw no one. He heard the noise again so he went downstairs and outdoors where he stood behind a bush and observed a light across the street behind a wooden door between the London Mills Drug Store and Boden’s Insurance Agency. Riley called the police, and later saw the policemen bring defendant and another man out from between the two buildings. Upon closer inspection of the premises, he saw a padlock broken off a storeroom door, and one off a basement door, and some wood trim from around a drugstore window on the floor. On cross-examination, defense counsel questioned Riley about a statement he gave to the police at 4:10 a.m. on March 14 in which he said he saw three men run around the drugstore building when he first looked out his window.
A Fulton County deputy sheriff described the arrest of defendant who was discovered crouched in a comer of the walkway separating the drug store from the insurance agency. The deputy said that defendant *465“was less than stable,” but he did not smell any alcohol although he did find some pipes used for smoking cannabis. He also stated no one was inside the building.
At the close of the State’s case the hearing was recessed until June 16, when defendant took the stand to testify in his own behalf as to count II. According to defendant, in the early morning of March 14, after becoming intoxicated while drinking beer with some friends, he and his friend Melvin Thomas were walking in a park in London Mills when a young man about defendant’s age, who he did not know, came up to them and asked if they would like to buy some cannabis. After defendant said he had no money, the stranger invited them to try some anyway and took them to the area behind the drugstore where they smoked a pipe. The stranger saw a squad car and ran away, but when defendant and Thomas heard a gunshot, they became frightened and went back between the buildings where they stayed until they were arrested. Defendant denied trying to get into the drugstore, and stated that he was under the influence of alcohol that night.
In closing argument defense counsel stated that the result as to count I was a foregone conclusion but that, as to count II, defendant was telling the truth “because he does not wish to admit to doing something he didn’t do having admitted already to something he did do and I am speaking now of Count I.”
The trial court ruled that defendant was guilty of violating his probation as to both count I and count II. At the sentencing hearing on July 28, the court imposed a sentence of two to six years in the penitentiary with credit for time in custody. On August 5, all parties again appeared in court at the request of the trial judge for the express purpose of clarifying the record to show that defendant is not to receive credit for the 14 months he spent on probation. Defense counsel objected that this amounted to an illegal increase in defendant’s sentence, but the trial judge persisted and called attention to the fact that because of his assignments to other counties, August 5 was the first time he had been able to return to Knox County to clarify the record. This appeal followed.
Defendant first contends that his confession was improperly admitted into evidence because the State did not produce all of the witnesses who were present at its taking. He cites People v. Armstrong (1972), 51 Ill. 2d 471, 282 N.E.2d 712, where a conviction was reversed for improper admission of the defendant’s confession. In Armstrong defendant filed a motion to suppress his confession, and at the hearing on the motion, defendant testified that his statement was made after he was repeatedly beaten by police while, in custody and that he was not advised of his rights. Defendant’s testimony was corroborated by several relatives. The State did not call all of the officers listed by defendant as participants in *466his arrest and interrogation and did not attempt to explain the absence of some of the officers. The Illinois Supreme Court reversed and restated the general rule that, when the voluntary nature of a confession is challenged by a motion to suppress, the State must produce all witnesses to the taking of the confession or must explain their absence. In relying on Armstrong and other cases where the issue of voluntariness was raised in the trial court, defendant ignores the rule that any question as to the voluntariness of a confession is waived if defendant does not raise the issue by motion to suppress or by objection at trial. (People v. Terrell (1975), 62 Ill. 2d 60, 338 N.E.2d 383; People v. Richardson (1st Dist. 1978), 61 Ill. App. 3d 718, 377 N.E.2d 1235; People v. Lee (2d Dist. 1976) , 41 Ill. App. 3d 502, 354 N.E.2d 543.) Since defendant did not claim in the trial court that his confession was involuntary, the issue cannot be raised for the first time on appeal.
Defendant discusses People v. Willis (1st Dist. 1975), 26 Ill. App. 3d 518, 325 N.E.2d 715, in support of the proposition that the State’s failure to call all the witnesses to a confession is reversible error whether the defendant objects at trial or not. Aside from the fact that Willis was decided before the supreme court’s decision to the contrary in Terrell, we think it significant that in Willis the voluntariness of the confession was raised in the trial court so that the statements which support defendant’s position are dicta at most. The same is true of People v. Bell (5th Dist. 1977), 50 Ill. App. 3d 82, 365 N.E.2d 203. We believe the principles enunciated by the supreme court in Terrell are controlling here. The State need not call as witnesses all of the persons present when a confession is taken unless the defendant places the question of voluntariness at issue in the trial court. Therefore, we find that defendant’s confession was properly admitted in this case.
Defendant next argues that he was denied effective assistance of counsel in that the public defender failed to challenge the confession, failed to develop a defense theory to refute count I and virtually conceded defendant’s guilt as to count I in closing argument. Defendant does not claim that the court erred in denying his motion for a continuance, although he does contend that counsel lacked adequate preparation for the revocation hearing. Competency of counsel is a factual question and will not be inferred from the fact that trial was commenced shortly after appointment of counsel. (People v. Gray (1965), 33 Ill. 2d 349, 211 N.E.2d 369.) Also the parties agreed to a four-week recess to allow defendant time to prepare his defense.
*467“In order to establish lack of competent representation at trial, it is necessary to demonstrate ‘actual incompetence of counsel, as reflected by the manner of carrying out his duties as a trial attorney’ which results in substantial prejudice without which the outcome would probably have been different.” 52 Ill. 2d 403, 409, 288 N.E.2d 416, 419.
Defendant suggests that we adopt, as a new standard to measure competency of counsel, the standard used by the Seventh Circuit Court of Appeals which is whether counsel’s conduct falls short of the expected professional standard of competent counsel. (United States ex rel. Williams v. Twomey (7th Cir. 1975), 510 F.2d 634.) The Illinois Supreme Court quite recently rejected the Federal standard in People v. Murphy (1978), 72 Ill. 2d 421, 381 N.E.2d 677, and we must do the same.
Defendant contends that his trial counsel’s closing argument was a “meaningless summation,” that he failed to object to introduction of the confession on the obvious ground that not all of material witnesses were present, and that he failed to formulate a “defense theory” as to either count.
After reviewing the record, we find that defendant was competently represented. Defense counsel cross-examined the State’s witnesses in an able manner and voiced appropriate objections to inadmissible testimony. Although defendant complains that counsel failed to defend on the burglary charge, there is nothing in the record to indicate defendant’s possible innocence or to indicate that defendant’s confession was not voluntary. Matters beyond the record cannot be a basis for a reversal, and defense counsel certainly had no duty to manufacture a defense where none existed. (People v. Conway (1st Dist. 1967), 85 Ill. App. 2d 165, 228 N.E. 548, cert. denied (1968), 393 U.S. 1006, 21 L. Ed. 2d 471, 89 S. Ct. 498.) The mere failure to make an objection is a matter of judgment and does not establish incompetency. “Competency is determined from the totality of counsel’s conduct of trial. * * * [Ejrrors in judgment on trial strategy do not establish incompetency.” (People v. Murphy (1978), 72 Ill. 2d 421, 437, 381 N.E.2d 677, 685-86.) The cases relied upon by defendant are not applicable to the case at bar because in those cases, the record contained testimony indicating that the confession might have been coerced while here there is nothing to support an assertion of involuntariness.
As to count II, defendant by his own testimony admitted being intoxicated on March 14 in London Mills; he admitted smoking marijuana that night; and he admitted being in the area behind the drugstore for 30 minutes; but he denied trying to break into the building. This state of facts did not give counsel many options in preparing a defense. Obviously *468counsel had to convince the court that defendant was telling the truth in the face of strong circumstantial evidence against him. We cannot fault counsel’s strategy.
Using Illinois’ two-pronged standard for measuring competency of counsel, we find nothing to indicate defense counsel’s actual incompetence in the performance of the duties of a trial attorney and, considering that the State’s burden was to prove defendant guilty of violating his probation by a preponderance of the evidence, and not beyond a reasonable doubt, defendant has failed to demonstrate substantial prejudice. We therefore hold that defendant received adequate representation.
The next error assigned is the trial court’s order of August 5 specifying that defendant is not to receive credit for the time successfully served on probation. Section 5 — 6—4(i) of the Unified Code of Corrections (Ill. Rev. Stat. 1977, ch. 38, par. 1005 — 6—4(i)) provides that, where probation has been revoked, time served on probation shall be credited against a sentence of imprisonment unless the court orders otherwise. Thus when the trial court first imposed a sentence of two to six years imprisonment without any mention of credit for time on probation, defendant was automatically entitled to 14 months credit. Defendant contends that the court’s August 5 action increased his sentence illegally. He cites section 5 — 8—1(d) of the Unified Code of Corrections (Ill. Rev. Stat. 1977, ch. 38, par. 1005 — 8—1(d)), which provides:
“The court may reduce or modify, but shall not increase the length of a sentence by order entered not later than 30 days from the date that sentence was imposed. This shall not enlarge the jurisdiction of the court for any other purpose.”
Aside from section 5 — 8—1(d), Illinois courts are bound by the rule that the trial court retains jurisdiction over a judgment for 30 days after it is rendered for purposes of correcting errors except that in criminal cases, the trial court loses jurisdiction when the defendant begins serving his sentence. (People v. Heil (1978), 71 Ill. 2d 458, 376 N.E.2d 1002; People v. Hamel (1946), 392 Ill. 415, 64 N.E.2d 865.) Where, as here, defendant is still in the county jail awaiting delivery to the penitentiary, the trial court retains the power and jurisdiction to vacate the judgment or to change it in material matters for proper cause shown. (People v. Watson (1946), 394 Ill. 177, 68 N.E.2d 265, cert. denied (1946), 329 U.S. 769, 91 L. Ed. 662, 67 S. Ct. 130.) Under that rule, the order of the trial court denying defendant credit for probation time would be perfectly proper since defendant had not yet begun to serve his sentence in the penitentiary.
Defendant insists that section 5 — 8—1(d) restricts the trial court to modifications which do not increase the time to be served, thus changing the rule as set out in Watson, Hamel and earlier cases. We do not agree. *469We interpret section 5 — 8—1(d) as giving the trial court the additional jurisdictional power to reduce or modify without increasing a sentence after defendant has begun serving his sentence until 30 days from the date sentence was imposed. We reach this conclusion in order to give effect to the last sentence of section 5 — 8—1(d) which says: "This shall not enlarge the jurisdiction of the court for any other purpose.” (Emphasis added.) This sentence must mean that the preceding sentence was intended to enlarge the jurisdiction of the court for the purpose of reducing or modifying a sentence within 30 days, and the only way jurisdiction could be enlarged would be by eliminating the previous restriction.
Accordingly, we hold that the modification of the trial court’s sentencing order was within the jurisdiction of the court and was not erroneous.
Finally defendant contends that the trial court abused its discretion when it imposed an enhanced sentence of two to six years for a Class 3 felony without taking into account defendant’s lack of a prior record or the circumstances of the crime. Defendant mentions that the quantity of MDA was small (.2 gram) and that he made no financial profit on the transaction. Considering the potential for serious trouble that could result from mailing drugs to a prison inmate, and considering that defendant’s conduct while on probation indicated a minimal potential for rehabilitation, we find no abuse of discretion by the trial court and can see no justification for intervening to reduce the sentence imposed. See People v. Perruquet (1977), 68 Ill. 2d 149, 368 N.E.2d 882.
For the reasons stated, we affirm the judgment of conviction and sentence entered by the Circuit Court of Knox County.
ALLOY, J., concurs.