diff --git a/gnss-converters.cabal b/gnss-converters.cabal
--- a/gnss-converters.cabal
+++ b/gnss-converters.cabal
@@ -1,5 +1,5 @@
 name:                  gnss-converters
-version:               0.2.0
+version:               0.2.1
 synopsis:              GNSS Converters.
 description:           Haskell bindings for GNSS converters.
 homepage:              http://github.com/swift-nav/gnss-converters
diff --git a/src/Data/RTCM3/SBP.hs b/src/Data/RTCM3/SBP.hs
--- a/src/Data/RTCM3/SBP.hs
+++ b/src/Data/RTCM3/SBP.hs
@@ -144,8 +144,8 @@
 maxObsPerMessage = (maxPayloadSize - headerSize) `div` packedObsSize
   where
     maxPayloadSize = 255
-    headerSize     = 7
-    packedObsSize  = 16
+    headerSize     = 11
+    packedObsSize  = 17
 
 
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