A method and mechanism for managing dynamically allocated memory. Portions of memory which are available for allocation have additional information stored in association with each portion which indicates whether the portion has been previously identified as being prematurely freed. In addition, a checksum is stored with each portion of memory. In response to a request for deallocation of a portion of memory, the portion of memory is not deallocated if it is identified as having been prematurely freed. Otherwise, the a checksum is calculated for the portion and it is freed. In response to an allocation request, a candidate portion of memory is identified for allocation and a checksum is calculated for the candidate portion. If the calculated checksum does not match a checksum previously stored for the candidate portion, the portion is identified as having been prematurely freed and is not returned for allocation.