diff --git a/netwerk/base/nsProtocolProxyService.cpp b/netwerk/base/nsProtocolProxyService.cpp
index ee21b9471093..d60738de5b30 100644
--- a/netwerk/base/nsProtocolProxyService.cpp
+++ b/netwerk/base/nsProtocolProxyService.cpp
@@ -75,7 +75,7 @@ struct nsProtocolInfo {
 static nsresult
 GetProxyURI(nsIChannel *channel, nsIURI **aOut)
 {
-  nsresult rv;
+  nsresult rv = NS_OK;
   nsCOMPtr<nsIURI> proxyURI;
   nsCOMPtr<nsIHttpChannelInternal> httpChannel(do_QueryInterface(channel));
   if (httpChannel) {
diff --git a/netwerk/dns/nsIDNService.cpp b/netwerk/dns/nsIDNService.cpp
index fe4a15f95264..25430f318343 100644
--- a/netwerk/dns/nsIDNService.cpp
+++ b/netwerk/dns/nsIDNService.cpp
@@ -506,7 +506,7 @@ static void ucs4toUtf16(const uint32_t *in, nsAString& out)
 static nsresult punycode(const nsAString& in, nsACString& out)
 {
   uint32_t ucs4Buf[kMaxDNSNodeLen + 1];
-  uint32_t ucs4Len;
+  uint32_t ucs4Len = 0u;
   nsresult rv = utf16ToUcs4(in, ucs4Buf, kMaxDNSNodeLen, &ucs4Len);
   NS_ENSURE_SUCCESS(rv, rv);
 
diff --git a/netwerk/protocol/http/Http2Compression.cpp b/netwerk/protocol/http/Http2Compression.cpp
index e67b59f1dfbb..ddb1a9f15b3d 100644
--- a/netwerk/protocol/http/Http2Compression.cpp
+++ b/netwerk/protocol/http/Http2Compression.cpp
@@ -1279,8 +1279,8 @@ Http2Compressor::ProcessHeader(const nvPair inputPair, bool noLocalIndex,
 {
   uint32_t newSize = inputPair.Size();
   uint32_t headerTableSize = mHeaderTable.Length();
-  uint32_t matchedIndex;
-  uint32_t nameReference = 0;
+  uint32_t matchedIndex = 0u;
+  uint32_t nameReference = 0u;
   bool match = false;
 
   LOG(("Http2Compressor::ProcessHeader %s %s", inputPair.mName.get(),