diff --git a/py/builtin.c b/py/builtin.c
index e723fad334..725613385a 100644
--- a/py/builtin.c
+++ b/py/builtin.c
@@ -36,6 +36,8 @@
 #include "runtime0.h"
 #include "runtime.h"
 #include "builtin.h"
+#include "stream.h"
+#include "pfenv.h"
 
 #if MICROPY_PY_BUILTINS_FLOAT
 #include <math.h>
@@ -424,13 +426,36 @@ STATIC mp_obj_t mp_builtin_print(uint n_args, const mp_obj_t *args, mp_map_t *kw
     if (end_elem != NULL && end_elem->value != mp_const_none) {
         end_data = mp_obj_str_get_data(end_elem->value, &end_len);
     }
+    #if MICROPY_PY_IO
+    mp_obj_t stream_obj = &mp_sys_stdout_obj;
+    mp_map_elem_t *file_elem = mp_map_lookup(kwargs, MP_OBJ_NEW_QSTR(MP_QSTR_file), MP_MAP_LOOKUP);
+    if (file_elem != NULL && file_elem->value != mp_const_none) {
+        stream_obj = file_elem->value;
+    }
+
+    pfenv_t pfenv;
+    pfenv.data = stream_obj;
+    pfenv.print_strn = (void (*)(void *, const char *, unsigned int))mp_stream_write;
+    #endif
     for (int i = 0; i < n_args; i++) {
         if (i > 0) {
+            #if MICROPY_PY_IO
+            mp_stream_write(stream_obj, sep_data, sep_len);
+            #else
             printf("%.*s", sep_len, sep_data);
+            #endif
         }
+        #if MICROPY_PY_IO
+        mp_obj_print_helper((void (*)(void *env, const char *fmt, ...))pfenv_printf, &pfenv, args[i], PRINT_STR);
+        #else
         mp_obj_print(args[i], PRINT_STR);
+        #endif
     }
+    #if MICROPY_PY_IO
+    mp_stream_write(stream_obj, end_data, end_len);
+    #else
     printf("%.*s", end_len, end_data);
+    #endif
     return mp_const_none;
 }
 
diff --git a/py/builtin.h b/py/builtin.h
index 361cef604e..425cfec097 100644
--- a/py/builtin.h
+++ b/py/builtin.h
@@ -81,5 +81,10 @@ extern const mp_obj_module_t mp_module_struct;
 extern const mp_obj_module_t mp_module_sys;
 extern const mp_obj_module_t mp_module_gc;
 
+struct _dummy_t;
+extern struct _dummy_t mp_sys_stdin_obj;
+extern struct _dummy_t mp_sys_stdout_obj;
+extern struct _dummy_t mp_sys_stderr_obj;
+
 // extmod modules
 extern const mp_obj_module_t mp_module_uctypes;
diff --git a/py/modsys.c b/py/modsys.c
index d215846762..c248e5626f 100644
--- a/py/modsys.c
+++ b/py/modsys.c
@@ -44,9 +44,6 @@
 // only addresses.
 struct _dummy_t;
 extern struct _dummy_t mp_sys_exit_obj;
-extern struct _dummy_t mp_sys_stdin_obj;
-extern struct _dummy_t mp_sys_stdout_obj;
-extern struct _dummy_t mp_sys_stderr_obj;
 
 extern mp_obj_int_t mp_maxsize_obj;
 
diff --git a/py/pfenv.h b/py/pfenv.h
index 22b1fc8492..781738f4db 100644
--- a/py/pfenv.h
+++ b/py/pfenv.h
@@ -49,3 +49,6 @@ int pfenv_print_mp_int(const pfenv_t *pfenv, mp_obj_t x, int sgn, int base, int
 #if MICROPY_PY_BUILTINS_FLOAT
 int pfenv_print_float(const pfenv_t *pfenv, mp_float_t f, char fmt, int flags, char fill, int width, int prec);
 #endif
+
+//int pfenv_vprintf(const pfenv_t *pfenv, const char *fmt, va_list args);
+int pfenv_printf(const pfenv_t *pfenv, const char *fmt, ...);
diff --git a/py/pfenv_printf.c b/py/pfenv_printf.c
new file mode 100644
index 0000000000..003314e8f5
--- /dev/null
+++ b/py/pfenv_printf.c
@@ -0,0 +1,199 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdarg.h>
+
+#include "mpconfig.h"
+#include "misc.h"
+#include "qstr.h"
+#include "obj.h"
+#include "pfenv.h"
+
+#if MICROPY_PY_BUILTINS_FLOAT
+#include "formatfloat.h"
+#endif
+
+int pfenv_vprintf(const pfenv_t *pfenv, const char *fmt, va_list args) {
+    int chrs = 0;
+    for (;;) {
+        {
+            const char *f = fmt;
+            while (*f != '\0' && *f != '%') {
+                ++f; // XXX UTF8 advance char
+            }
+            if (f > fmt) {
+                pfenv->print_strn(pfenv->data, fmt, f - fmt);
+                chrs += f - fmt;
+                fmt = f;
+            }
+        }
+
+        if (*fmt == '\0') {
+            break;
+        }
+
+        // move past % character
+        ++fmt;
+
+        // parse flags, if they exist
+        int flags = 0;
+        char fill = ' ';
+        while (*fmt != '\0') {
+            if (*fmt == '-') flags |= PF_FLAG_LEFT_ADJUST;
+            else if (*fmt == '+') flags |= PF_FLAG_SHOW_SIGN;
+            else if (*fmt == ' ') flags |= PF_FLAG_SPACE_SIGN;
+            else if (*fmt == '!') flags |= PF_FLAG_NO_TRAILZ;
+            else if (*fmt == '0') {
+                flags |= PF_FLAG_PAD_AFTER_SIGN;
+                fill = '0';
+            } else break;
+            ++fmt;
+        }
+
+        // parse width, if it exists
+        int width = 0;
+        for (; '0' <= *fmt && *fmt <= '9'; ++fmt) {
+            width = width * 10 + *fmt - '0';
+        }
+
+        // parse precision, if it exists
+        int prec = -1;
+        if (*fmt == '.') {
+            ++fmt;
+            if (*fmt == '*') {
+                ++fmt;
+                prec = va_arg(args, int);
+            } else {
+                prec = 0;
+                for (; '0' <= *fmt && *fmt <= '9'; ++fmt) {
+                    prec = prec * 10 + *fmt - '0';
+                }
+            }
+            if (prec < 0) {
+                prec = 0;
+            }
+        }
+
+        // parse long specifiers (current not used)
+        //bool long_arg = false;
+        if (*fmt == 'l') {
+            ++fmt;
+            //long_arg = true;
+        }
+
+        if (*fmt == '\0') {
+            break;
+        }
+
+        switch (*fmt) {
+            case 'b':
+                if (va_arg(args, int)) {
+                    chrs += pfenv_print_strn(pfenv, "true", 4, flags, fill, width);
+                } else {
+                    chrs += pfenv_print_strn(pfenv, "false", 5, flags, fill, width);
+                }
+                break;
+            case 'c':
+            {
+                char str = va_arg(args, int);
+                chrs += pfenv_print_strn(pfenv, &str, 1, flags, fill, width);
+                break;
+            }
+            case 's':
+            {
+                const char *str = va_arg(args, const char*);
+                if (str) {
+                    if (prec < 0) {
+                        prec = strlen(str);
+                    }
+                    chrs += pfenv_print_strn(pfenv, str, prec, flags, fill, width);
+                } else {
+                    chrs += pfenv_print_strn(pfenv, "(null)", 6, flags, fill, width);
+                }
+                break;
+            }
+            case 'u':
+                chrs += pfenv_print_int(pfenv, va_arg(args, int), 0, 10, 'a', flags, fill, width);
+                break;
+            case 'd':
+                chrs += pfenv_print_int(pfenv, va_arg(args, int), 1, 10, 'a', flags, fill, width);
+                break;
+            case 'x':
+            case 'p': // ?
+                chrs += pfenv_print_int(pfenv, va_arg(args, int), 0, 16, 'a', flags, fill, width);
+                break;
+            case 'X':
+            case 'P': // ?
+                chrs += pfenv_print_int(pfenv, va_arg(args, int), 0, 16, 'A', flags, fill, width);
+                break;
+#if MICROPY_PY_BUILTINS_FLOAT
+            case 'e':
+            case 'E':
+            case 'f':
+            case 'F':
+            case 'g':
+            case 'G':
+            {
+#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
+                mp_float_t f = va_arg(args, double);
+                chrs += pfenv_print_float(pfenv, f, *fmt, flags, fill, width, prec);
+#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
+                // Currently pfenv_print_float uses snprintf, but snprintf
+                // itself may be implemented in terms of pfenv_vprintf() for
+                // some ports. So, for extra caution, this case is handled
+                // with assert below. Note that currently ports which
+                // use MICROPY_FLOAT_IMPL_DOUBLE, don't call pfenv_vprintf()
+                // with float format specifier at all.
+                // TODO: resolve this completely
+                assert(0);
+//#error Calling pfenv_print_float with double not supported from within printf
+#else
+#error Unknown MICROPY FLOAT IMPL
+#endif
+                break;
+            }
+#endif
+            default:
+                pfenv->print_strn(pfenv->data, fmt, 1);
+                chrs += 1;
+                break;
+        }
+        ++fmt;
+    }
+    return chrs;
+}
+
+int pfenv_printf(const pfenv_t *pfenv, const char *fmt, ...) {
+    va_list ap;
+    va_start(ap, fmt);
+    int ret = pfenv_vprintf(pfenv, fmt, ap);
+    va_end(ap);
+    return ret;
+}
diff --git a/py/py.mk b/py/py.mk
index 1615c4bbaa..f1ae3c3f1e 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -102,6 +102,7 @@ PY_O_BASENAME = \
 	repl.o \
 	smallint.o \
 	pfenv.o \
+	pfenv_printf.o \
 	../extmod/moductypes.o
 
 # prepend the build destination prefix to the py object files
diff --git a/py/qstrdefs.h b/py/qstrdefs.h
index e3a4dc01ab..0deb646c7b 100644
--- a/py/qstrdefs.h
+++ b/py/qstrdefs.h
@@ -413,6 +413,7 @@ Q(TextIOWrapper)
 Q(StringIO)
 Q(BytesIO)
 Q(getvalue)
+Q(file)
 #endif
 
 #if MICROPY_PY_GC
diff --git a/stmhal/printf.c b/stmhal/printf.c
index c4731aa88d..d998a6277d 100644
--- a/stmhal/printf.c
+++ b/stmhal/printf.c
@@ -45,156 +45,12 @@
 #include "formatfloat.h"
 #endif
 
+int pfenv_vprintf(const pfenv_t *pfenv, const char *fmt, va_list args);
+
 void pfenv_prints(const pfenv_t *pfenv, const char *str) {
     pfenv->print_strn(pfenv->data, str, strlen(str));
 }
 
-int pfenv_printf(const pfenv_t *pfenv, const char *fmt, va_list args) {
-    int chrs = 0;
-    for (;;) {
-        {
-            const char *f = fmt;
-            while (*f != '\0' && *f != '%') {
-                ++f; // XXX UTF8 advance char
-            }
-            if (f > fmt) {
-                pfenv->print_strn(pfenv->data, fmt, f - fmt);
-                chrs += f - fmt;
-                fmt = f;
-            }
-        }
-
-        if (*fmt == '\0') {
-            break;
-        }
-
-        // move past % character
-        ++fmt;
-
-        // parse flags, if they exist
-        int flags = 0;
-        char fill = ' ';
-        while (*fmt != '\0') {
-            if (*fmt == '-') flags |= PF_FLAG_LEFT_ADJUST;
-            else if (*fmt == '+') flags |= PF_FLAG_SHOW_SIGN;
-            else if (*fmt == ' ') flags |= PF_FLAG_SPACE_SIGN;
-            else if (*fmt == '!') flags |= PF_FLAG_NO_TRAILZ;
-            else if (*fmt == '0') {
-                flags |= PF_FLAG_PAD_AFTER_SIGN;
-                fill = '0';
-            } else break;
-            ++fmt;
-        }
-
-        // parse width, if it exists
-        int width = 0;
-        for (; '0' <= *fmt && *fmt <= '9'; ++fmt) {
-            width = width * 10 + *fmt - '0';
-        }
-
-        // parse precision, if it exists
-        int prec = -1;
-        if (*fmt == '.') {
-            ++fmt;
-            if (*fmt == '*') {
-                ++fmt;
-                prec = va_arg(args, int);
-            } else {
-                prec = 0;
-                for (; '0' <= *fmt && *fmt <= '9'; ++fmt) {
-                    prec = prec * 10 + *fmt - '0';
-                }
-            }
-            if (prec < 0) {
-                prec = 0;
-            }
-        }
-
-        // parse long specifiers (current not used)
-        //bool long_arg = false;
-        if (*fmt == 'l') {
-            ++fmt;
-            //long_arg = true;
-        }
-
-        if (*fmt == '\0') {
-            break;
-        }
-
-        switch (*fmt) {
-            case 'b':
-                if (va_arg(args, int)) {
-                    chrs += pfenv_print_strn(pfenv, "true", 4, flags, fill, width);
-                } else {
-                    chrs += pfenv_print_strn(pfenv, "false", 5, flags, fill, width);
-                }
-                break;
-            case 'c':
-            {
-                char str = va_arg(args, int);
-                chrs += pfenv_print_strn(pfenv, &str, 1, flags, fill, width);
-                break;
-            }
-            case 's':
-            {
-                const char *str = va_arg(args, const char*);
-                if (str) {
-                    if (prec < 0) {
-                        prec = strlen(str);
-                    }
-                    chrs += pfenv_print_strn(pfenv, str, prec, flags, fill, width);
-                } else {
-                    chrs += pfenv_print_strn(pfenv, "(null)", 6, flags, fill, width);
-                }
-                break;
-            }
-            case 'u':
-                chrs += pfenv_print_int(pfenv, va_arg(args, int), 0, 10, 'a', flags, fill, width);
-                break;
-            case 'd':
-                chrs += pfenv_print_int(pfenv, va_arg(args, int), 1, 10, 'a', flags, fill, width);
-                break;
-            case 'x':
-            case 'p': // ?
-                chrs += pfenv_print_int(pfenv, va_arg(args, int), 0, 16, 'a', flags, fill, width);
-                break;
-            case 'X':
-            case 'P': // ?
-                chrs += pfenv_print_int(pfenv, va_arg(args, int), 0, 16, 'A', flags, fill, width);
-                break;
-#if MICROPY_PY_BUILTINS_FLOAT
-            case 'e':
-            case 'E':
-            case 'f':
-            case 'F':
-            case 'g':
-            case 'G':
-            {
-#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
-                mp_float_t f = va_arg(args, double);
-                chrs += pfenv_print_float(pfenv, f, *fmt, flags, fill, width, prec);
-#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
-                // Currently pfenv_print_float uses snprintf, so if you want
-                // to use pfenv_print_float with doubles then you'll need
-                // fix it to not use snprintf first. Otherwise you'll have
-                // inifinite recursion.
-#error Calling pfenv_print_float with double not supported from within printf
-#else
-#error Unknown MICROPY FLOAT IMPL
-#endif
-                break;
-            }
-#endif
-            default:
-                pfenv->print_strn(pfenv->data, fmt, 1);
-                chrs += 1;
-                break;
-        }
-        ++fmt;
-    }
-    return chrs;
-}
-
 STATIC void stdout_print_strn(void *data, const char *str, unsigned int len) {
     // TODO this needs to be replaced with a proper stdio interface ala CPython
     // send stdout to UART and USB CDC VCP
@@ -211,13 +67,13 @@ static const pfenv_t pfenv_stdout = {0, stdout_print_strn};
 int printf(const char *fmt, ...) {
     va_list ap;
     va_start(ap, fmt);
-    int ret = pfenv_printf(&pfenv_stdout, fmt, ap);
+    int ret = pfenv_vprintf(&pfenv_stdout, fmt, ap);
     va_end(ap);
     return ret;
 }
 
 int vprintf(const char *fmt, va_list ap) {
-    return pfenv_printf(&pfenv_stdout, fmt, ap);
+    return pfenv_vprintf(&pfenv_stdout, fmt, ap);
 }
 
 #if MICROPY_DEBUG_PRINTERS