diff --git a/src/nt_encoding.cpp b/src/nt_encoding.cpp
index 8a6ac9ab0c..60603e5aa0 100644
--- a/src/nt_encoding.cpp
+++ b/src/nt_encoding.cpp
@@ -29,21 +29,6 @@ NtImpl::WriteDouble(char* &buf, double val)
     *buf++ = (char)(v & 0xff);
 }
 
-double
-NtImpl::ReadDouble(char* &buf)
-{
-    std::uint64_t val = (*((unsigned char *)buf)) & 0xff;
-    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
-    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
-    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
-    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
-    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
-    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
-    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
-    ++buf;
-    return *reinterpret_cast<double*>(&val);
-}
-
 size_t
 NT_WriteType(char *buf, NT_Type type, unsigned int proto_rev)
 {
diff --git a/src/nt_encoding.h b/src/nt_encoding.h
index f7ca8c569f..f2c8c30fc8 100644
--- a/src/nt_encoding.h
+++ b/src/nt_encoding.h
@@ -62,8 +62,6 @@ Read32(char* &buf)
     return val;
 }
 
-double ReadDouble(char* &buf);
-
 } // namespace NtImpl
 
 #endif /* NT_UTIL_H */
diff --git a/src/nt_raw_istream.cpp b/src/nt_raw_istream.cpp
index 59a2237899..6ac0839a79 100644
--- a/src/nt_raw_istream.cpp
+++ b/src/nt_raw_istream.cpp
@@ -7,9 +7,22 @@
 
 #include "nt_raw_istream.h"
 
+#include <cstring>
+
 using namespace NtImpl;
 
 void
 raw_istream::anchor()
 {
 }
+
+bool
+raw_mem_istream::read(void *data, std::size_t len)
+{
+    if (len > m_left)
+        return false;
+    std::memcpy(data, m_cur, len);
+    m_cur += len;
+    m_left -= len;
+    return true;
+}
diff --git a/src/nt_raw_istream.h b/src/nt_raw_istream.h
index af0a715183..58be85db07 100644
--- a/src/nt_raw_istream.h
+++ b/src/nt_raw_istream.h
@@ -16,6 +16,7 @@ class raw_istream
 {
     void anchor();
 public:
+    raw_istream() {}
     virtual ~raw_istream() {}
     virtual bool read(void *data, std::size_t len) = 0;
     virtual void close() = 0;
@@ -24,6 +25,20 @@ private:
     raw_istream& operator= (const raw_istream&);
 };
 
+class raw_mem_istream : public raw_istream
+{
+public:
+    raw_mem_istream(const char *mem, std::size_t len)
+        : m_cur(mem), m_left(len)
+    {}
+    virtual ~raw_mem_istream() {}
+    virtual bool read(void *data, std::size_t len);
+    virtual void close() {}
+private:
+    const char *m_cur;
+    std::size_t m_left;
+};
+
 } // namespace NtImpl
 
 #endif /* NT_RAW_ISTREAM_H_ */
diff --git a/src/nt_wiredecoder.cpp b/src/nt_wiredecoder.cpp
index 730e5f7b1d..11c6a7d66c 100644
--- a/src/nt_wiredecoder.cpp
+++ b/src/nt_wiredecoder.cpp
@@ -17,6 +17,21 @@
 
 using namespace NtImpl;
 
+static double
+read_double(char* &buf)
+{
+    std::uint64_t val = (*((unsigned char *)buf)) & 0xff;
+    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
+    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
+    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
+    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
+    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
+    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
+    ++buf; val <<= 8; val |= (*((unsigned char *)buf)) & 0xff;
+    ++buf;
+    return *reinterpret_cast<double*>(&val);
+}
+
 WireDecoder::WireDecoder(raw_istream& is, unsigned int proto_rev)
     : m_is(is)
 {
@@ -31,6 +46,15 @@ WireDecoder::~WireDecoder()
     std::free(m_buf);
 }
 
+bool
+WireDecoder::ReadDouble(double *val)
+{
+    char *buf;
+    if (!Read(&buf, 8)) return false;
+    *val = read_double(buf);
+    return true;
+}
+
 void
 WireDecoder::Realloc(std::size_t len)
 {
@@ -124,7 +148,7 @@ WireDecoder::ReadValue(NT_Type type, NT_Value *value)
         value->data.arr_double.arr =
                 (double *)std::malloc(size * sizeof(double));
         for (unsigned int i=0; i<size; ++i)
-            value->data.arr_double.arr[i] = NtImpl::ReadDouble(buf);
+            value->data.arr_double.arr[i] = read_double(buf);
         break;
     }
     case NT_STRING_ARRAY:
diff --git a/src/nt_wiredecoder.h b/src/nt_wiredecoder.h
index 751cf2ddff..15e75b77b2 100644
--- a/src/nt_wiredecoder.h
+++ b/src/nt_wiredecoder.h
@@ -70,13 +70,7 @@ public:
         return true;
     }
 
-    bool ReadDouble(double *val)
-    {
-        char *buf;
-        if (!Read(&buf, 8)) return false;
-        *val = NtImpl::ReadDouble(buf);
-        return true;
-    }
+    bool ReadDouble(double *val);
 
     bool ReadULEB128(unsigned long *val)
     {