  We study the change in the temperature of maximum density (TMD) of a
water-like solvent when small amounts of solute are added to the mixture. The
water is modeled as a two length scales potential, which is known to exhibit
water-like characteristic anomalies, while the solute is chosen to have an
attractive interaction with the solvent. If the solute is a structure maker the
TMD increases with the addition of solute, while if it is a structure breaker
the TMD decreases. Both in an exact one dimensional model and using molecular
dynamics in three dimensions we show that the necessary ingredient to represent
structure makers is a strong solute-solvent attraction.
