diff --git a/automation/release/nspr-version.txt b/automation/release/nspr-version.txt
index 102def16d9..b91871c6ed 100644
--- a/automation/release/nspr-version.txt
+++ b/automation/release/nspr-version.txt
@@ -1,4 +1,4 @@
-4.20
+4.21
 
 # The first line of this file must contain the human readable NSPR
 # version number, which is the minimum required version of NSPR