diff --git a/include/netcdf.h b/include/netcdf.h
index 6ba8ba48be..3dfcb7ae21 100644
--- a/include/netcdf.h
+++ b/include/netcdf.h
@@ -17,7 +17,7 @@ See \ref copyright file for more info.
 #include <errno.h>  /* netcdf functions sometimes return system errors */
 
 /* Required for alloca on Windows */
-#if defined(_WIN32) || defined(_WIN64)
+#if defined(_WIN32)
 #include <malloc.h>
 #endif
 
diff --git a/include/onstack.h b/include/onstack.h
index bd3b8e39e9..578495d563 100644
--- a/include/onstack.h
+++ b/include/onstack.h
@@ -63,7 +63,7 @@
 
 # define FREE_ONSTACK(name)
 
-#elif defined(_WIN32) || defined(_WIN64)
+#elif defined(_WIN32)
 #include <malloc.h>
 #undef ALLOCA_ARG_T
 # define ALLOCA_ARG_T size_t
diff --git a/libdap4/d4util.c b/libdap4/d4util.c
index 9a966cb469..ad02a265e4 100644
--- a/libdap4/d4util.c
+++ b/libdap4/d4util.c
@@ -381,7 +381,7 @@ NCD4_mktmp(const char* base, char** tmpnamep)
 	if(rno < 0) rno = -rno;
         snprintf(spid,sizeof(spid),"%06d",rno);
         strncat(tmp,spid,sizeof(tmp));
-#if defined(_WIN32) || defined(_WIN64)
+#ifdef _WIN32
         fd=open(tmp,O_RDWR|O_BINARY|O_CREAT, _S_IREAD|_S_IWRITE);
 #  else
         fd=open(tmp,O_RDWR|O_CREAT|O_EXCL, S_IRWXU);
diff --git a/libdap4/ncd4dispatch.c b/libdap4/ncd4dispatch.c
index 9dc764a7ce..e59d74882d 100644
--- a/libdap4/ncd4dispatch.c
+++ b/libdap4/ncd4dispatch.c
@@ -6,7 +6,7 @@
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
-#if defined(_WIN32) || defined(_WIN64)
+#ifdef _WIN32
 #include <crtdbg.h>
 #include <direct.h>
 #endif
diff --git a/libdispatch/ddispatch.c b/libdispatch/ddispatch.c
index 81e8506a55..edccac6bca 100644
--- a/libdispatch/ddispatch.c
+++ b/libdispatch/ddispatch.c
@@ -61,7 +61,7 @@ NCDISPATCH_initialize(void)
 	char* p;
 	char* q;
 	char cwd[4096];
-#ifdef _MSC_VER
+#ifdef _WIN32
         tempdir = getenv("TEMP");
 #else
 	tempdir = "/tmp";
diff --git a/libdispatch/dfile.c b/libdispatch/dfile.c
index 72d424a43c..6eab9d84f3 100644
--- a/libdispatch/dfile.c
+++ b/libdispatch/dfile.c
@@ -2178,3 +2178,169 @@ nc__pseudofd(void)
     }
     return pseudofd++;
 }
+
+/**
+\internal
+\ingroup datasets
+Provide open, read and close for use when searching for magic numbers
+*/
+static int
+openmagic(struct MagicFile* file)
+{
+    int status = NC_NOERR;
+    assert((!file->diskless && file->inmemory) ? file->parameters != NULL : 1);
+    if(file->inmemory && !file->diskless) {
+	/* Get its length */
+	NC_memio* meminfo = (NC_memio*)file->parameters;
+	file->filelen = (long long)meminfo->size;
+	goto done;
+    }
+#ifdef USE_PARALLEL
+    if (file->use_parallel) {
+	int retval;
+	MPI_Offset size;
+        assert(file->parameters);
+	if((retval = MPI_File_open(((NC_MPI_INFO*)file->parameters)->comm,
+                                   (char*)file->path,MPI_MODE_RDONLY,
+                                   ((NC_MPI_INFO*)file->parameters)->info,
+                                   &file->fh)) != MPI_SUCCESS)
+	    {status = NC_EPARINIT; goto done;}
+	/* Get its length */
+	if((retval=MPI_File_get_size(file->fh, &size)) != MPI_SUCCESS)
+	    {status = NC_EPARINIT; goto done;}
+	file->filelen = (long long)size;
+	goto done;
+    }
+#endif /* USE_PARALLEL */
+    {
+        if(file->path == NULL || strlen(file->path)==0)
+	    {status = NC_EINVAL; goto done;}
+#ifdef _WIN32
+        file->fp = fopen(file->path, "rb");
+#else
+        file->fp = fopen(file->path, "r");
+#endif
+	if(file->fp == NULL)
+	    {status = errno; goto done;}
+	/* Get its length */
+	{
+	int fd = fileno(file->fp);
+#ifdef _MSC_VER
+	__int64 len64 = _filelengthi64(fd);
+	if(len64 < 0)
+            {status = errno; goto done;}
+	file->filelen = (long long)len64;
+#else
+	off_t size;
+	size = lseek(fd, 0, SEEK_END);
+	if(size == -1)
+	    {status = errno; goto done;}
+	file->filelen = (long long)size;
+#endif
+	rewind(file->fp);
+	}
+	goto done;
+    }
+
+done:
+    return status;
+}
+
+static int
+readmagic(struct MagicFile* file, long pos, char* magic)
+{
+    int status = NC_NOERR;
+    memset(magic,0,MAGIC_NUMBER_LEN);
+    if(file->inmemory && !file->diskless) {
+	char* mempos;
+	NC_memio* meminfo = (NC_memio*)file->parameters;
+	if((pos + MAGIC_NUMBER_LEN) > meminfo->size)
+	    {status = NC_EDISKLESS; goto done;}
+	mempos = ((char*)meminfo->memory) + pos;
+	memcpy((void*)magic,mempos,MAGIC_NUMBER_LEN);
+#ifdef DEBUG
+	printmagic("XXX: readmagic",magic,file);
+#endif
+	goto done;
+    }
+#ifdef USE_PARALLEL
+    if (file->use_parallel) {
+	MPI_Status mstatus;
+	int retval;
+	if((retval = MPI_File_read_at_all(file->fh, pos, magic,
+                     MAGIC_NUMBER_LEN, MPI_CHAR, &mstatus)) != MPI_SUCCESS)
+	    {status = NC_EPARINIT; goto done;}
+	goto done;
+    }
+#endif /* USE_PARALLEL */
+    {
+	int count;
+	int i = fseek(file->fp,pos,SEEK_SET);
+	if(i < 0)
+	    {status = errno; goto done;}
+	for(i=0;i<MAGIC_NUMBER_LEN;) {/* make sure to read proper # of bytes */
+	    count=fread(&magic[i],1,(size_t)(MAGIC_NUMBER_LEN-i),file->fp);
+	    if(count == 0 || ferror(file->fp))
+		{status = errno; goto done;}
+	    i += count;
+	}
+	goto done;
+    }
+done:
+    if(file && file->fp) clearerr(file->fp);
+    return status;
+}
+
+/**
+ * Close the file opened to check for magic number.
+ *
+ * @param file pointer to the MagicFile struct for this open file.
+ * @returns NC_NOERR for success
+ * @returns NC_EPARINIT if there was a problem closing file with MPI
+ * (parallel builds only).
+ * @author Dennis Heimbigner
+ */
+static int
+closemagic(struct MagicFile* file)
+{
+    int status = NC_NOERR;
+    if(file->inmemory) goto done; /* noop*/
+#ifdef USE_PARALLEL
+    if (file->use_parallel) {
+	int retval;
+	if((retval = MPI_File_close(&file->fh)) != MPI_SUCCESS)
+		{status = NC_EPARINIT; goto done;}
+	goto done;
+    }
+#endif
+    {
+	if(file->fp) fclose(file->fp);
+	goto done;
+    }
+done:
+    return status;
+}
+
+#ifdef DEBUG
+static void
+printmagic(const char* tag, char* magic, struct MagicFile* f)
+{
+    int i;
+    fprintf(stderr,"%s: inmem=%d ispar=%d magic=",tag,f->inmemory,f->use_parallel);
+    for(i=0;i<MAGIC_NUMBER_LEN;i++) {
+        unsigned int c = (unsigned int)magic[i];
+	c = c & 0x000000FF;
+	if(c == '\n')
+	    fprintf(stderr," 0x%0x/'\\n'",c);
+	else if(c == '\r')
+	    fprintf(stderr," 0x%0x/'\\r'",c);
+	else if(c < ' ')
+	    fprintf(stderr," 0x%0x/'?'",c);
+	else
+	    fprintf(stderr," 0x%0x/'%c'",c,c);
+    }
+    fprintf(stderr,"\n");
+    fflush(stderr);
+}
+#endif
+
diff --git a/libdispatch/dutil.c b/libdispatch/dutil.c
index e4df1ea7b9..2420297d2a 100644
--- a/libdispatch/dutil.c
+++ b/libdispatch/dutil.c
@@ -163,6 +163,32 @@ NC_entityescape(const char* s)
     return escaped;
 }
 
+int
+NC_readfile(const char* filename, NCbytes* content)
+{
+    int ret = NC_NOERR;
+    FILE* stream = NULL;
+    char part[1024];
+
+#ifdef _WIN32
+    stream = NCfopen(filename,"rb");
+#else
+    stream = NCfopen(filename,"r");
+#endif
+    if(stream == NULL) {ret=errno; goto done;}
+    for(;;) {
+	size_t count = fread(part, 1, sizeof(part), stream);
+	if(count <= 0) break;
+	ncbytesappendn(content,part,count);
+	if(ferror(stream)) {ret = NC_EIO; goto done;}
+	if(feof(stream)) break;
+    }
+    ncbytesnull(content);
+done:
+    if(stream) fclose(stream);
+    return ret;
+}
+
 /**
 Wrap mktmp and return the generated path,
 or null if failed.
@@ -213,7 +239,7 @@ NC_mktmp(const char* base)
             strncat(tmp,spid,sizeof(tmp) - strlen(tmp) - 1);
 	}
 #endif /* HAVE_MKTEMP */
-#ifdef _MSC_VER
+#ifdef _WIN32
         fd=NCopen3(tmp,O_RDWR|O_BINARY|O_CREAT, _S_IREAD|_S_IWRITE);
 #else
         fd=NCopen3(tmp,O_RDWR|O_CREAT|O_EXCL, S_IRWXU);
diff --git a/libsrc/memio.c b/libsrc/memio.c
index 35bcd5738c..43f9437e02 100644
--- a/libsrc/memio.c
+++ b/libsrc/memio.c
@@ -144,7 +144,7 @@ memio_new(const char* path, int ioflags, off_t initialsize, ncio** nciopp, NCMEM
     assert(path != NULL);
 
     if(pagesize == 0) {
-#if defined (_WIN32) || defined(_WIN64)
+#if defined (_WIN32) && !defined(__MINGW32__)
       SYSTEM_INFO info;
       GetSystemInfo (&info);
       pagesize = info.dwPageSize;
diff --git a/libsrc/posixio.c b/libsrc/posixio.c
index ed7993b222..9eff6097e8 100644
--- a/libsrc/posixio.c
+++ b/libsrc/posixio.c
@@ -27,7 +27,7 @@
 #endif
 
 /* Windows platforms, including MinGW, Cygwin, Visual Studio */
-#if defined(_WIN32) || defined(_WIN64)
+#ifdef _WIN32
 #include <windows.h>
 #include <winbase.h>
 #include <io.h>
@@ -146,7 +146,7 @@ static size_t
 pagesize(void)
 {
   size_t pgsz;
-#if defined(_WIN32) || defined(_WIN64)
+#if defined(_WIN32)
   SYSTEM_INFO info;
 #endif
 /* Hmm, aren't standards great? */
@@ -155,7 +155,7 @@ pagesize(void)
 #endif
 
   /* For MinGW Builds */
-#if defined(_WIN32) || defined(_WIN64)
+#if defined(_WIN32)
   GetSystemInfo(&info);
   pgsz = (size_t)info.dwPageSize;
 #elif defined(_SC_PAGESIZE)
diff --git a/nc_test/test_read.m4 b/nc_test/test_read.m4
index 4434d6d312..02a3e9f24a 100644
--- a/nc_test/test_read.m4
+++ b/nc_test/test_read.m4
@@ -19,7 +19,7 @@ dnl (MPI_Offset vs. size_t), and function name substrings for external data
 dnl types.
 dnl
 
-#if defined (_WIN32) || defined (_WIN64)
+#ifdef _WIN32
 #include <io.h>
 #endif
 
diff --git a/nc_test/test_write.m4 b/nc_test/test_write.m4
index 4650e37067..a335a01559 100644
--- a/nc_test/test_write.m4
+++ b/nc_test/test_write.m4
@@ -19,7 +19,7 @@ dnl (MPI_Offset vs. size_t), and function name substrings for external data
 dnl types.
 dnl
 
-#if defined (_WIN32) || defined (_WIN64)
+#ifdef _WIN32
 #include <io.h>
 #endif
 
diff --git a/nc_test/tst_diskless5.c b/nc_test/tst_diskless5.c
index ab06f36df3..80c336de62 100644
--- a/nc_test/tst_diskless5.c
+++ b/nc_test/tst_diskless5.c
@@ -14,7 +14,7 @@ See \ref copyright file for more info.
 #include <stdio.h>
 #include <assert.h>
 #include <sys/types.h>
-#if defined (_WIN32) || defined (_WIN64) || defined _MSC_VER
+#ifdef _WIN32
 #include <io.h>
 #else
 #include <unistd.h>
diff --git a/nc_test4/tst_atts1.c b/nc_test4/tst_atts1.c
index b35a304a5f..87b3643c5b 100644
--- a/nc_test4/tst_atts1.c
+++ b/nc_test4/tst_atts1.c
@@ -352,7 +352,7 @@ main(int argc, char **argv)
       /* for (i = 0; i < ATT_LEN; i++) */
       /* 	  if (float_in[i] != (float) longlong_out[i]) ERR; */
       if (nc_get_att_float(ncid, NC_GLOBAL, ATT_UINT64_NAME, float_in)) ERR;
-#if !defined(_WIN32) && !defined(_WIN64)
+#ifndef _WIN32
 	  for (i = 0; i < ATT_LEN; i++)
 	  if (float_in[i] != (float) ulonglong_out[i]) ERR;
 #endif
diff --git a/nc_test4/tst_udf.c b/nc_test4/tst_udf.c
index ebe5437808..e976339291 100644
--- a/nc_test4/tst_udf.c
+++ b/nc_test4/tst_udf.c
@@ -15,7 +15,7 @@
 
 #define FILE_NAME "tst_udf.nc"
 
-#if defined(_WIN32) || defined(_WIN64)
+#ifdef _WIN32
 int
 NC4_show_metadata(int ncid)
 {