MEMORANDUM OPINION AND ORDER

Jerzy Lutkowski (“Jerzy”) and his wife Elizabeth (“Elizabeth”) — collectively “Lut-kowskis” — have brought a five-count Complaint against High Energy Sports, claiming damages as a result of injuries that Jerzy assertedly sustained in Burlington, Wisconsin while operating a hang-glider manufactured and distributed by High Energy Sports. Based on its initial review of the Complaint,1 this Court sua sponte dismisses the Complaint for lack of subject matter jurisdiction — but without prejudice to the possible prompt curing of the flaws identified in this opinion.

Lutkowskis seek to ground federal jurisdiction in diversity of citizenship under 28 U.S.C. §§ 1332(a)(1) and 1332(c)(1).2 Each of the Complaint’s counts asserts an ad damnum in excess of $50,000, thus satisfying (at least in facial terms) the jurisdictional amount for those purposes. And Complaint II1 properly identifies Lutkow-skis’ Illinois citizenship. But what Complaint 112 says about High Energy Sports’ citizenship is only this:

The Defendant, HIGH ENERGY SPORTS, is a foreign corporation, duly incorporated in the State of California.

Incorporation in California tells only half of the corporate citizenship story as defined by Section 1332(c)(1). What is missing from the Complaint is any identification of High Energy Sports’ principal place of business. It may perhaps be a reasonable inference from the remaining allegation of Complaint ¶ 2 (which speaks of the corporation’s business as including the placing of its products into the stream of commerce by multiple transactions in the state of Illinois) that this state does not fit the “principal place of business” description— but inferences (even highly probable ones), *225as contrasted with affirmative allegations, are not enough to establish jurisdiction here.

That pleading defect deprives this Court of independent subject matter jurisdiction over this action, for federal courts can deal with cases only as Congress specifies and as a plaintiffs express allegations bring the case within those specifications. See, e.g., 5 Wright & Miller, Federal Practice and Procedure: Civil § 1208, at 103-04 and n. 12, and cases there cited (1990 ed. and 1991 pocket part); 13 B id. § 3624, at 610 & n. 20, and cases there cited (1984 ed. and 1991 pocket part). Federal jurisdiction cannot be based on surmise or guesswork, and that is all this Court has available to it here.

Even though that constitutes a subject matter jurisdictional flaw that requires dismissal of the Complaint, it does seem most likely to be curable as permitted under Section 1653. For that reason this Court’s customary practice in such situations is to grant leave to cure the defect by an amended complaint. Indeed, that would appear especially appropriate here, because the Complaint was filed on the second anniversary of the alleged occurrence (which means that if the Illinois statute of limitations applies, a new lawsuit could be out of time3).

There is however another serious potential problem posed by the Complaint in its present form. Complaint It 2, with its allegation as to High Energy Sports being “engaged in the business of placing certain products into the stream of commerce within the State of Illinois and in multiple transactions place into the stream of commerce which were physically present within the State of Illinois on the date of the occurrence herein complained of,”4 obviously seeks to invoke the long-arm concepts embodied in Ill.Rev.Stat. ch. 110, ¶ 2-209(a). But that predicate for personal jurisdiction is limited to causes of action that “lie in the wake” of the Illinois-related conduct — the phrase used in the case law to express the limitation prescribed by id. ¶ 2-209(c) (see such cases, e.g., as Financial Management Services, Inc. v. Sibilsky & Sibilsky, Inc., 130 Ill.App.3d 826, 833, 86 Ill.Dec. 100, 106, 474 N.E.2d 1297, 1303 (1st Dist. 1985) and — applying Illinois law — Diamond Mortgage Corp. of Illinois v. Sugar, 913 F.2d 1233, 1245 (7th Cir. 1990) and cases cited there).

In this instance Jerzy was allegedly operating a High Energy Sports hang-glider at a recreational park in Wisconsin, and there is no allegation that Jerzy (if he owned the hang-glider5) had bought it in Illinois or that the owner (if Jerzy were simply operating it on a rental basis) had done so. Under those circumstances no predicate appears for obtaining personal jurisdiction over High Energy Sports on this Wisconsin-based claim in this State of Illinois. Certainly Complaint 112 alone would not be enough to do the job.6

Under the circumstances this Complaint is dismissed (as it must be for the reason stated at the outset) for lack of subject matter jurisdiction. Such dismissal is without prejudice to Lutkowskis’ filing of an amended complaint in this Court’s chambers on or before June 24, 1991 that both *226cures the defective allegations as to diversity of citizenship and addresses the other problem identified in this opinion. If no such pleading is filed, this action will itself be dismissed on June 25, 1991 on the same jurisdictional ground.