Methods of cementing in a subterranean formation include passing a swelling agent to a permeable zone in a subterranean formation. The swelling agent is combined with a carrier fluid before being passed to the permeable zone. Upon contacting an aqueous fluid, the swelling agent swells in the permeable zone. The aqueous fluid may already be present in the subterranean formation, or alternatively, it may be introduced to the subterranean formation after passing the swelling agent into the subterranean formation. The swelling agent substantially inhibits a cement slurry subsequently pumped into the subterranean formation from passing through the permeable zone. The cement slurry therefore continues flowing down through the casing and up through the annulus where it sets and forms a strong cement column.