diff --git a/intl/strres/src/nsStringBundle.cpp b/intl/strres/src/nsStringBundle.cpp
index 5a7a50f7be76..53cb270fff1a 100644
--- a/intl/strres/src/nsStringBundle.cpp
+++ b/intl/strres/src/nsStringBundle.cpp
@@ -24,6 +24,8 @@
 #include "nsIComponentManager.h"
 #include "nsIMemory.h"
 #include "nsIObserverService.h"
+#include "pratom.h"
+#include "prmem.h"
 #include "nsCOMArray.h"
 #include "nsTextFormatter.h"
 #include "nsIErrorService.h"
diff --git a/netwerk/base/src/nsSerializationHelper.cpp b/netwerk/base/src/nsSerializationHelper.cpp
index 146ee99188b2..82ff90bf420e 100644
--- a/netwerk/base/src/nsSerializationHelper.cpp
+++ b/netwerk/base/src/nsSerializationHelper.cpp
@@ -4,8 +4,9 @@
 
 #include "nsSerializationHelper.h"
 
+#include "plbase64.h"
+#include "prmem.h"
 
-#include "mozilla/Base64.h"
 #include "nsISerializable.h"
 #include "nsIObjectOutputStream.h"
 #include "nsIObjectInputStream.h"
@@ -15,8 +16,6 @@
 #include "nsComponentManagerUtils.h"
 #include "nsStringStream.h"
 
-using namespace mozilla;
-
 nsresult
 NS_SerializeToString(nsISerializable* obj, nsCSubstring& str)
 {
@@ -39,12 +38,30 @@ NS_SerializeToString(nsISerializable* obj, nsCSubstring& str)
 nsresult
 NS_DeserializeObject(const nsCSubstring& str, nsISupports** obj)
 {
-  nsCString decodedData;
-  nsresult rv = Base64Decode(str, decodedData);
-  NS_ENSURE_SUCCESS(rv, rv);
+  // Base64 maps 3 binary bytes -> 4 ASCII bytes.  If the original byte array
+  // does not have length 0 mod 3, the input is padded with zeros and the
+  // output is padded with a corresponding number of trailing '=' (which are
+  // then sometimes dropped).  To compute the correct length of the original
+  // byte array, we have to subtract the number of trailing '=' and then
+  // multiply by 3 and then divide by 4 (making sure this is an integer
+  // division).
 
+  uint32_t size = str.Length();
+  if (size > 0 && str[size-1] == '=') {
+    if (size > 1 && str[size-2] == '=') {
+      size -= 2;
+    } else {
+      size -= 1;
+    }
+  }
+  size = (size * 3) / 4;
+  char* buf = PL_Base64Decode(str.BeginReading(), str.Length(), nullptr);
+  if (!buf)
+    return NS_ERROR_OUT_OF_MEMORY;
   nsCOMPtr<nsIInputStream> stream;
-  rv = NS_NewCStringInputStream(getter_AddRefs(stream), decodedData);
+  nsresult rv = NS_NewCStringInputStream(getter_AddRefs(stream),
+                                         Substring(buf, size));
+  PR_Free(buf);
   NS_ENSURE_SUCCESS(rv, rv);
 
   nsCOMPtr<nsIObjectInputStream> objstream =
diff --git a/netwerk/base/src/nsSocketTransport2.cpp b/netwerk/base/src/nsSocketTransport2.cpp
index a348eb59b117..8e0b45efa7be 100644
--- a/netwerk/base/src/nsSocketTransport2.cpp
+++ b/netwerk/base/src/nsSocketTransport2.cpp
@@ -19,6 +19,7 @@
 #include "nsAutoPtr.h"
 #include "nsCOMPtr.h"
 #include "netCore.h"
+#include "prmem.h"
 #include "plstr.h"
 #include "prnetdb.h"
 #include "prerror.h"
diff --git a/netwerk/cache/nsCacheMetaData.cpp b/netwerk/cache/nsCacheMetaData.cpp
index d7dc37a32e7e..929117e8473d 100644
--- a/netwerk/cache/nsCacheMetaData.cpp
+++ b/netwerk/cache/nsCacheMetaData.cpp
@@ -6,6 +6,7 @@
 
 #include "nsCacheMetaData.h"
 #include "nsICacheEntryDescriptor.h"
+#include "prmem.h"
 
 const char *
 nsCacheMetaData::GetElement(const char * key)
@@ -151,7 +152,7 @@ nsresult
 nsCacheMetaData::EnsureBuffer(uint32_t bufSize)
 {
     if (mBufferSize < bufSize) {
-        char * buf = (char *)moz_realloc(mBuffer, bufSize);
+        char * buf = (char *)PR_REALLOC(mBuffer, bufSize);
         if (!buf) {
             return NS_ERROR_OUT_OF_MEMORY;
         }
diff --git a/netwerk/cache/nsCacheMetaData.h b/netwerk/cache/nsCacheMetaData.h
index e0879c1473f2..6bd7b995d2e6 100644
--- a/netwerk/cache/nsCacheMetaData.h
+++ b/netwerk/cache/nsCacheMetaData.h
@@ -18,8 +18,7 @@ public:
 
     ~nsCacheMetaData() {
         mBufferSize = mMetaSize = 0;  
-        moz_free(mBuffer);
-        mBuffer = nullptr;
+        PR_FREEIF(mBuffer);
     }
 
     const char *  GetElement(const char * key);
diff --git a/netwerk/protocol/data/nsDataChannel.cpp b/netwerk/protocol/data/nsDataChannel.cpp
index 9a68c7f27af2..2699b787fe49 100644
--- a/netwerk/protocol/data/nsDataChannel.cpp
+++ b/netwerk/protocol/data/nsDataChannel.cpp
@@ -5,10 +5,8 @@
 
 // data implementation
 
-#include "nsDataChannel.h"
-
-#include "mozilla/Base64.h"
 #include "nsIOService.h"
+#include "nsDataChannel.h"
 #include "nsDataHandler.h"
 #include "nsNetUtil.h"
 #include "nsIPipe.h"
@@ -16,8 +14,9 @@
 #include "nsIOutputStream.h"
 #include "nsReadableUtils.h"
 #include "nsEscape.h"
-
-using namespace mozilla;
+#include "plbase64.h"
+#include "plstr.h"
+#include "prmem.h"
 
 nsresult
 nsDataChannel::OpenContentStream(bool async, nsIInputStream **result,
@@ -71,10 +70,17 @@ nsDataChannel::OpenContentStream(bool async, nsIInputStream **result,
         }
         resultLen = ((resultLen * 3) / 4);
 
-        nsAutoCString decodedData;
-        rv = Base64Decode(dataBuffer, decodedData);
-        NS_ENSURE_SUCCESS(rv, rv);
-        rv = bufOutStream->Write(decodedData.get(), resultLen, &contentLen);
+        // XXX PL_Base64Decode will return a null pointer for decoding
+        // errors.  Since those are more likely than out-of-memory,
+        // should we return NS_ERROR_MALFORMED_URI instead?
+        char * decodedData = PL_Base64Decode(dataBuffer.get(), dataLen, nullptr);
+        if (!decodedData) {
+            return NS_ERROR_OUT_OF_MEMORY;
+        }
+
+        rv = bufOutStream->Write(decodedData, resultLen, &contentLen);
+
+        PR_Free(decodedData);
     } else {
         rv = bufOutStream->Write(dataBuffer.get(), dataBuffer.Length(), &contentLen);
     }