Abstract: To increase the resistance of a tubular compact fluorescent lamp against akage, particularly at the cross-connecting portion (4) of a U-bent discharge vessel having two leg portions (2, 3), the cross-connecting portion is shaped to have generally parabolic cross section, in which the cross-sectional area of the parabola is about the same as the cross-sectional area of the generally circular leg portions of the U-shaped discharge vessel (1). This provides for better distribution of the glass material of which the discharge tube is made, and hence greater resistance to breakage. The parabolic cross section is terminated at the inner side of the U-bend by an essentially flat, or slightly curved base surface (16), merging with rounded corners (16a) with the parabolic side surfaces. Preferably, the relationship of the radius of curvature (R.sub.P) at the apex of the parabola to the radius of curvature (R.sub.