diff --git a/CHANGELOG b/CHANGELOG
index a2739b94a..1d4681e77 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,8 @@
 #Nmap Changelog ($Id$); -*-text-*-
 
+o [NSE][GH#1209] Fix SIP, SASL, and HTTP Digest authentication when the algorithm
+  contains lowercase characters. [Jeswin Mathai]
+
 o [GH#1204] Nmap could be fooled into ignoring TCP response packets if they
   used an unknown TCP Option, which would misalign the validation, causing it
   to fail. [Clément Notin, Daniel Miller]
diff --git a/nselib/sasl.lua b/nselib/sasl.lua
index 1d5565c3c..a73ac3ad0 100644
--- a/nselib/sasl.lua
+++ b/nselib/sasl.lua
@@ -127,7 +127,7 @@ if HAVE_SSL then
         qop .. ":" .. A2))
 
       local b1
-      if not self.challnvs.algorithm or self.challnvs.algorithm == "MD5" then
+      if not self.challnvs.algorithm or self.challnvs.algorithm:upper() == "MD5" then
         b1 = stdnse.tohex(openssl.md5(self.username..":"..(self.challnvs.realm or "")..":"..self.password))
       else
         b1 = A1
diff --git a/nselib/sip.lua b/nselib/sip.lua
index d1f986fb1..73bb66dac 100644
--- a/nselib/sip.lua
+++ b/nselib/sip.lua
@@ -804,7 +804,7 @@ SipAuth = {
     assert(self.uri, "SipAuth: No uri specified")
 
     local result
-    if ( self.algorithm == "MD5" ) then
+    if ( self.algorithm:upper() == "MD5" ) then
       local HA1 = select(2, bin.unpack("H16", openssl.md5(self.username .. ":" .. self.realm .. ":" .. self.password)))
       local HA2 = select(2, bin.unpack("H16", openssl.md5(self.method .. ":" .. self.uri)))
       result = openssl.md5(HA1:lower() .. ":" .. self.nonce ..":" .. HA2:lower())