Datacenter TCP (DCTCP) achieves low latencies for short flows while maintaining high throughputs for concurrent bulk transfers, but requires changes to both endpoints, which presents a deployment challenge. This presentation introduces extensions to DCTCP that enables one-sided deployment when peers implement standard TCP/ECN functionality. This makes DCTCP significantly easier to deploy incrementally. We also improve DCTCP in two-sided deployments by refining ECN processing and the calculation of the congestion estimate. A FreeBSD kernel implementation of these DCTCP improvements demonstrates better performance than the original DCTCP variant, and validates that incremental one-sided deployments see benefits similar to those previously only achievable in two-sided deployments.