diff --git a/assemble.c b/assemble.c
index 8cd72d9e..20e35c27 100644
--- a/assemble.c
+++ b/assemble.c
@@ -511,7 +511,7 @@ int64_t assemble(int32_t segment, int64_t offset, int bits, iflag_t cp,
         const char *fname = instruction->eops->stringval;
         FILE *fp;
 
-        fp = fopen(fname, "rb");
+        fp = nasm_open_read(fname, NF_BINARY);
         if (!fp) {
             nasm_error(ERR_NONFATAL, "`incbin': unable to open file `%s'",
                   fname);
@@ -806,7 +806,7 @@ int64_t insn_size(int32_t segment, int64_t offset, int bits, iflag_t cp,
         int64_t val = 0;
         size_t len;
 
-        fp = fopen(fname, "rb");
+        fp = nasm_open_read(fname, NF_BINARY);
         if (!fp)
             nasm_error(ERR_NONFATAL, "`incbin': unable to open file `%s'",
                   fname);
diff --git a/listing.c b/listing.c
index 27d16ed1..084386dc 100644
--- a/listing.c
+++ b/listing.c
@@ -132,7 +132,7 @@ static void list_init(const char *fname)
 	return;
     }
 
-    listfp = fopen(fname, "w");
+    listfp = nasm_open_write(fname, NF_TEXT);
     if (!listfp) {
 	nasm_error(ERR_NONFATAL, "unable to open listing file `%s'",
 		   fname);
diff --git a/nasm.c b/nasm.c
index e39e1e94..3ed3bfdb 100644
--- a/nasm.c
+++ b/nasm.c
@@ -290,7 +290,7 @@ static void emit_dependencies(StrList *list)
     StrList *l, *nl;
 
     if (depend_file && strcmp(depend_file, "-")) {
-        deps = fopen(depend_file, "w");
+        deps = nasm_open_write(depend_file, NF_TEXT);
         if (!deps) {
             nasm_error(ERR_NONFATAL|ERR_NOFILE|ERR_USAGE,
                        "unable to write dependency file `%s'", depend_file);
@@ -406,7 +406,7 @@ int main(int argc, char **argv)
             int lineinc = 0;
 
             if (*outname) {
-                ofile = fopen(outname, "w");
+                ofile = nasm_open_write(outname, NF_TEXT);
                 if (!ofile)
                     nasm_fatal(ERR_NOFILE,
                                  "unable to open output file `%s'",
@@ -459,7 +459,7 @@ int main(int argc, char **argv)
          */
         ofmt->filename(inname, outname);
 
-        ofile = fopen(outname, (ofmt->flags & OFMT_TEXT) ? "w" : "wb");
+        ofile = nasm_open_write(outname, (ofmt->flags & OFMT_TEXT) ? NF_TEXT : NF_BINARY);
         if (!ofile)
             nasm_fatal(ERR_NOFILE,
                        "unable to open output file `%s'", outname);
@@ -1106,7 +1106,7 @@ static void process_args(char *args)
 static void process_response_file(const char *file)
 {
     char str[2048];
-    FILE *f = fopen(file, "r");
+    FILE *f = nasm_open_read(file, NF_TEXT);
     if (!f) {
         perror(file);
         exit(-1);
@@ -1159,7 +1159,7 @@ static void parse_cmdline(int argc, char **argv)
         if (!stopoptions && argv[0][0] == '-' && argv[0][1] == '@') {
             p = get_param(argv[0], argc > 1 ? argv[1] : NULL, &advance);
             if (p) {
-                rfile = fopen(p, "r");
+                rfile = nasm_open_read(p, NF_TEXT);
                 if (rfile) {
                     process_respfile(rfile);
                     fclose(rfile);
@@ -1188,7 +1188,7 @@ static void parse_cmdline(int argc, char **argv)
                    inname);
 
     if (*errname) {
-        error_file = fopen(errname, "w");
+        error_file = nasm_open_write(errname, NF_TEXT);
         if (!error_file) {
             error_file = stderr;        /* Revert to default! */
             nasm_fatal(ERR_NOFILE | ERR_USAGE,
diff --git a/nasmlib.h b/nasmlib.h
index 9d0904b4..cf4a919a 100644
--- a/nasmlib.h
+++ b/nasmlib.h
@@ -434,6 +434,19 @@ char *nasm_realpath(const char *rel_path);
 
 const char *prefix_name(int);
 
+/*
+ * Wrappers around fopen()... for future change to a dedicated structure
+ */
+enum file_flags {
+    NF_BINARY	= 0x00000000,   /* Binary file (default) */
+    NF_TEXT	= 0x00000001,   /* Text file */
+    NF_NONFATAL = 0x00000000,   /* Don't die on open failure (default) */
+    NF_FATAL    = 0x00000002    /* Die on open failure */
+};
+
+FILE *nasm_open_read(const char *filename, enum file_flags flags);
+FILE *nasm_open_write(const char *filename, enum file_flags flags);
+
 #define ZERO_BUF_SIZE 4096      /* Default value */
 #if defined(BUFSIZ) && (BUFSIZ > ZERO_BUF_SIZE)
 # undef ZERO_BUF_SIZE
diff --git a/nasmlib/file.c b/nasmlib/file.c
index 6ba38444..8c35f0e1 100644
--- a/nasmlib/file.c
+++ b/nasmlib/file.c
@@ -153,3 +153,38 @@ void fwritezero(size_t bytes, FILE *fp)
 	bytes -= blksize;
     }
 }
+
+#ifdef __GLIBC__
+/* If we are using glibc, attempt to mmap the files for speed */
+# define READ_TEXT_FILE "rtm"
+# define READ_BIN_FILE  "rbm"
+#else
+# define READ_TEXT_FILE "rt"
+# define READ_BIN_FILE  "rb"
+#endif
+#define WRITE_TEXT_FILE "wt"
+#define WRITE_BIN_FILE  "wb"
+
+FILE *nasm_open_read(const char *filename, enum file_flags flags)
+{
+    FILE *f;
+
+    f = fopen(filename, (flags & NF_TEXT) ? READ_TEXT_FILE : READ_BIN_FILE);
+    if (!f && (flags & NF_FATAL))
+        nasm_fatal(ERR_NOFILE, "unable to open input file: `%s': %s",
+                   filename, strerror(errno));
+
+    return f;
+}
+
+FILE *nasm_open_write(const char *filename, enum file_flags flags)
+{
+    FILE *f;
+
+    f = fopen(filename, (flags & NF_TEXT) ? WRITE_TEXT_FILE : WRITE_BIN_FILE);
+    if (!f && (flags & NF_FATAL))
+        nasm_fatal(ERR_NOFILE, "unable to open output file: `%s': %s",
+                   filename, strerror(errno));
+
+    return f;
+}
diff --git a/ndisasm.c b/ndisasm.c
index d90b5c3b..9356270b 100644
--- a/ndisasm.c
+++ b/ndisasm.c
@@ -271,7 +271,7 @@ int main(int argc, char **argv)
     }
 
     if (strcmp(filename, "-")) {
-        fp = fopen(filename, "rb");
+        fp = nasm_open_read(filename, NF_BINARY);
         if (!fp) {
             fprintf(stderr, "%s: unable to open `%s': %s\n",
                     pname, filename, strerror(errno));
diff --git a/output/codeview.c b/output/codeview.c
index 945e2225..d3c72ae3 100644
--- a/output/codeview.c
+++ b/output/codeview.c
@@ -341,7 +341,7 @@ static void calc_md5(const char *const filename,
     FILE *f;
     MD5_CTX ctx;
 
-    f = pp_input_fopen(filename, "rb");
+    f = pp_input_fopen(filename, NF_BINARY);
     if (!f)
         goto done;
 
diff --git a/output/outbin.c b/output/outbin.c
index 3e1ec286..fa76f605 100644
--- a/output/outbin.c
+++ b/output/outbin.c
@@ -1347,7 +1347,7 @@ static int bin_directive(enum directives directive, char *args, int pass)
                 else if (!nasm_stricmp(p, "stderr"))
                     rf = stderr;
                 else {          /* Must be a filename. */
-                    rf = fopen(p, "wt");
+                    rf = nasm_open_write(p, NF_TEXT);
                     if (!rf) {
                         nasm_error(ERR_WARNING, "unable to open map file `%s'",
                               p);
diff --git a/preproc-nop.c b/preproc-nop.c
index b3f9b0d2..1cb14457 100644
--- a/preproc-nop.c
+++ b/preproc-nop.c
@@ -61,7 +61,7 @@ static void nop_reset(char *file, int pass, StrList **deplist)
 {
     src_set(0, file);
     nop_lineinc = 1;
-    nop_fp = fopen(file, "r");
+    nop_fp = nasm_open_read(file, NF_TEXT);
 
     if (!nop_fp)
 	nasm_fatal(ERR_NOFILE, "unable to open input file `%s'", file);
diff --git a/preproc.c b/preproc.c
index 845f8fc1..e36ae9c9 100644
--- a/preproc.c
+++ b/preproc.c
@@ -1507,7 +1507,7 @@ static bool in_list(const StrList *list, const char *str)
  * the end of the path.
  */
 static FILE *inc_fopen(const char *file, StrList **dhead, StrList ***dtail,
-                       bool missing_ok, const char *mode)
+                       bool missing_ok, enum file_flags mode)
 {
     FILE *fp;
     char *prefix = "";
@@ -1520,7 +1520,7 @@ static FILE *inc_fopen(const char *file, StrList **dhead, StrList ***dtail,
         sl = nasm_malloc(prefix_len+len+1+sizeof sl->next);
         memcpy(sl->str, prefix, prefix_len);
         memcpy(sl->str+prefix_len, file, len+1);
-        fp = fopen(sl->str, mode);
+        fp = nasm_open_read(sl->str, mode);
         if (fp && dhead && !in_list(*dhead, sl->str)) {
             sl->next = NULL;
             **dtail = sl;
@@ -1562,7 +1562,7 @@ static FILE *inc_fopen(const char *file, StrList **dhead, StrList ***dtail,
  * that get a file:lineno pair and need to look at the file again
  * (e.g. the CodeView debug backend). Returns NULL on failure.
  */
-FILE *pp_input_fopen(const char *filename, const char *mode)
+FILE *pp_input_fopen(const char *filename, enum file_flags mode)
 {
     FILE *fp;
     StrList *xsl = NULL;
@@ -2515,7 +2515,7 @@ static int do_directive(Token * tline)
         inc = nasm_malloc(sizeof(Include));
         inc->next = istk;
         inc->conds = NULL;
-        inc->fp = inc_fopen(p, dephead, &deptail, pass == 0, "r");
+        inc->fp = inc_fopen(p, dephead, &deptail, pass == 0, NF_TEXT);
         if (!inc->fp) {
             /* -MG given but file not found */
             nasm_free(inc);
@@ -3258,7 +3258,7 @@ issue_error:
         if (t->type != TOK_INTERNAL_STRING)
             nasm_unquote(p, NULL);
 
-        fp = inc_fopen(p, &xsl, &xst, true, "r");
+        fp = inc_fopen(p, &xsl, &xst, true, NF_TEXT);
         if (fp) {
             p = xsl->str;
             fclose(fp);         /* Don't actually care about the file */
@@ -4851,7 +4851,7 @@ pp_reset(char *file, int apass, StrList **deplist)
     istk->conds = NULL;
     istk->expansion = NULL;
     istk->mstk = NULL;
-    istk->fp = fopen(file, "r");
+    istk->fp = nasm_open_read(file, NF_TEXT);
     istk->fname = NULL;
     src_set(0, file);
     istk->lineinc = 1;
diff --git a/preproc.h b/preproc.h
index 3d1aa9c7..fcf8695b 100644
--- a/preproc.h
+++ b/preproc.h
@@ -38,6 +38,7 @@
 #ifndef NASM_PREPROC_H
 #define NASM_PREPROC_H
 
+#include "nasmlib.h"
 #include "pptok.h"
 
 extern const char * const pp_directives[];
@@ -49,6 +50,6 @@ typedef const unsigned char macros_t;
 enum preproc_token pp_token_hash(const char *token);
 
 /* Opens an include file or input file. This uses the include path. */
-FILE *pp_input_fopen(const char *filename, const char *mode);
+FILE *pp_input_fopen(const char *filename, enum file_flags mode);
 
 #endif