  Molecular hydrogen (H2) absorption features observed in the line-of-sight to
Q2348-011 at redshift zabs = 2.426 are analysed for the purpose of detecting a
possible variation of the proton-to-electron mass ratio mu=mp/me. By its
structure Q2348-011 is the most complex analysed H2 absorption system at high
redshift so far, featuring at least seven distinctly visible molecular velocity
components. The multiple velocity components associated with each transition of
H2 were modeled simultaneously by means of a comprehensive fitting method. The
fiducial model resulted in dmu/mu = (-0.68 +/- 2.78) x 10^-5, showing no sign
that mu in this particular absorber is different from its current laboratory
value. Although not as tight a constraint as other absorbers have recently
provided, this result is consistent with the results from all previously
analysed H2-bearing sight-lines. Combining all such measurements yields a
constraint of dmu/mu < 10^-5 for the redshift range z = (2--3).
