diff --git a/mercurial/manifest.c b/mercurial/manifest.c
--- a/mercurial/manifest.c
+++ b/mercurial/manifest.c
@@ -440,6 +440,8 @@ static int internalsetitem(lazymanifest 
 		else {
 			if (self->lines[pos].deleted)
 				self->livelines++;
+			if (self->lines[pos].from_malloc)
+				free(self->lines[pos].start);
 			start = pos;
 			goto finish;
 		}