diff --git a/c_src/Makefile b/c_src/Makefile
index 169408a..4d71801 100644
--- a/c_src/Makefile
+++ b/c_src/Makefile
@@ -5,7 +5,7 @@ UNAME	:= $(shell uname -s)
 TAR		?= tar
 GUNZIP		?= gunzip
 SMONKEY_VER	:= 1.8.0-rc1
-NSPR_VER	:= 4.8
+NSPR_VER	:= 4.21
 
 ifeq ($(UNAME),SunOS)
 	PATCH	?= gpatch
diff --git a/c_src/nsprpub-4.21.tar.gz b/c_src/nsprpub-4.21.tar.gz
new file mode 100644
index 0000000..66cd924
Binary files /dev/null and b/c_src/nsprpub-4.21.tar.gz differ
diff --git a/c_src/nsprpub-4.8.tar.gz b/c_src/nsprpub-4.8.tar.gz
deleted file mode 100644
index 6f7bdd2..0000000
Binary files a/c_src/nsprpub-4.8.tar.gz and /dev/null differ