diff --git a/README.md b/README.md
index aa9f156..c5e4c24 100644
--- a/README.md
+++ b/README.md
@@ -490,6 +490,7 @@ The patch binary formats have additional standard header information:
     byte:         endianness (1 = NDR, 0 = XDR)
     uint32:       pcid (key to POINTCLOUD_SCHEMAS)
     uint32:       0 = no compression
+    uint32:        npoints
     pointdata[]:  interpret relative to pcid
 
 ### Patch Binary (Dimensional) ###