diff --git a/deps.bzl b/deps.bzl
index 20d808ef840..59bde0b54a7 100644
--- a/deps.bzl
+++ b/deps.bzl
@@ -728,8 +728,8 @@ def prysm_deps():
         name = "com_github_ferranbt_fastssz",
         importpath = "github.com/ferranbt/fastssz",
         nofuzz = True,
-        sum = "h1:lBcqQHaZyB0AYEUohFpsIDWY1sHo28VgGXOCBdnPCWo=",
-        version = "v0.0.0-20210107123522-4c3c34260bd9",
+        sum = "h1:Xun9jB2EhB8JZbVhjpW7/o6pLEwXb89tHkN8Q08kEZM=",
+        version = "v0.0.0-20210118190430-6ca267833c4b",
     )
 
     go_repository(
diff --git a/go.mod b/go.mod
index 89ffc4d3504..d6027597dbf 100644
--- a/go.mod
+++ b/go.mod
@@ -20,7 +20,7 @@ require (
 	github.com/emicklei/dot v0.11.0
 	github.com/ethereum/go-ethereum v0.0.0-00010101000000-000000000000
 	github.com/fatih/color v1.9.0 // indirect
-	github.com/ferranbt/fastssz v0.0.0-20210107123522-4c3c34260bd9
+	github.com/ferranbt/fastssz v0.0.0-20210118190430-6ca267833c4b
 	github.com/fjl/memsize v0.0.0-20190710130421-bcb5799ab5e5
 	github.com/fsnotify/fsnotify v1.4.9
 	github.com/gballet/go-libpcsclite v0.0.0-20191108122812-4678299bea08 // indirect
diff --git a/go.sum b/go.sum
index c0389b1af62..c3efb9aec7f 100644
--- a/go.sum
+++ b/go.sum
@@ -248,8 +248,8 @@ github.com/fatih/color v1.9.0/go.mod h1:eQcE1qtQxscV5RaZvpXrrb8Drkc3/DdQ+uUYCNjL
 github.com/ferranbt/fastssz v0.0.0-20200728110133-0b6e349af87a/go.mod h1:DyEu2iuLBnb/T51BlsiO3yLYdJC6UbGMrIkqK1KmQxM=
 github.com/ferranbt/fastssz v0.0.0-20201020132831-68dc48984fd3 h1:FnpkCo1TAj/eq0ETLPhAplYYB4KlFQy3kVb8cLludAc=
 github.com/ferranbt/fastssz v0.0.0-20201020132831-68dc48984fd3/go.mod h1:DyEu2iuLBnb/T51BlsiO3yLYdJC6UbGMrIkqK1KmQxM=
-github.com/ferranbt/fastssz v0.0.0-20210107123522-4c3c34260bd9 h1:lBcqQHaZyB0AYEUohFpsIDWY1sHo28VgGXOCBdnPCWo=
-github.com/ferranbt/fastssz v0.0.0-20210107123522-4c3c34260bd9/go.mod h1:DyEu2iuLBnb/T51BlsiO3yLYdJC6UbGMrIkqK1KmQxM=
+github.com/ferranbt/fastssz v0.0.0-20210118190430-6ca267833c4b h1:Xun9jB2EhB8JZbVhjpW7/o6pLEwXb89tHkN8Q08kEZM=
+github.com/ferranbt/fastssz v0.0.0-20210118190430-6ca267833c4b/go.mod h1:DyEu2iuLBnb/T51BlsiO3yLYdJC6UbGMrIkqK1KmQxM=
 github.com/fjl/memsize v0.0.0-20180418122429-ca190fb6ffbc/go.mod h1:VvhXpOYNQvB+uIk2RvXzuaQtkQJzzIx6lSBe1xv7hi0=
 github.com/fjl/memsize v0.0.0-20190710130421-bcb5799ab5e5 h1:FtmdgXiUlNeRsoNMFlKLDt+S+6hbjVMEW6RGQ7aUf7c=
 github.com/fjl/memsize v0.0.0-20190710130421-bcb5799ab5e5/go.mod h1:VvhXpOYNQvB+uIk2RvXzuaQtkQJzzIx6lSBe1xv7hi0=