We further analyze the definition and the calculation of
 the heavy quark impact factor at next-to-leading (NL)
 $\log s$ level, and we provide its analytical expression
 in a previously proposed k-factorization scheme. 
 Our results indicate that k-factorization holds at NL level
 with a properly chosen energy scale, and with the same gluonic
 Green's function previously found in the massless probe case.