diff --git a/src/ciabatta.c b/src/ciabatta.c
index fef13f1..c38a1ab 100644
--- a/src/ciabatta.c
+++ b/src/ciabatta.c
@@ -50,7 +50,7 @@
 #include "conv/strpfx.c"
 #include "conv/int.c"
 #include "conv/float.c"
-#include "fmt/gen_fmt.c"
+#include "fmt/fmt.c"
 #include "stdlib/algorithm.c"
 #include "stdlib/multibyte.c"
 #include "stdlib/random.c"
diff --git a/src/fmt/fmt.c b/src/fmt/fmt.c
new file mode 100644
index 0000000..ace1a88
--- /dev/null
+++ b/src/fmt/fmt.c
@@ -0,0 +1,164 @@
+
+#define FLAG_ZERO   0x0001 // "0"
+#define FLAG_LEFT   0x0002 // "-"
+#define FLAG_PLUS   0x0004 // "+"
+#define FLAG_SPACE  0x0008 // " "
+#define FLAG_HASH   0x0010 // "#"
+#define FLAG_PREC   0x0020 // ".precision"
+#define FLAG_LONG   0x0040 // "l"
+#define FLAG_LLONG  0x0080 // "ll"
+#define FLAG_SHORT  0x0100 // "h"
+#define FLAG_CHAR   0x0200 // "hh"
+#define FLAG_UPPER  0x0400 // for hex digits 0xa-0xf
+
+struct fmt_t typedef fmt_t;
+struct fmt_t {
+    int prec;
+    int width;
+    int flags;
+};
+
+#define ctype  char
+#define pfx(f) f
+#include "fmt_string.h"
+#include "fmt_stream.h"
+#include "ints.h"
+#include "fmt.h"
+#undef  ctype
+#undef  pfx
+
+#define ctype  wchar_t
+#define pfx(f) w ## f
+#include "fmt_string.h"
+#include "fmt_stream.h"
+#include "ints.h"
+#include "fmt.h"
+#undef  ctype
+#undef  pfx
+
+// fprintf family
+
+static inline int fstream_outc(void *ctx, char c) {
+    FILE *file = ctx;
+    int result = fputc(c, file);
+    if(result == EOF) {
+        return -1;
+    }
+    return 1;
+}
+
+static inline int fstream_outw(void *ctx, wchar c) {
+    FILE *file = ctx;
+    int result = fputc((char)c, file); // TODO: utf8
+    if(result == EOF) {
+        return -1;
+    }
+    return 1;
+}
+
+static inline fmt_stream_t fstream_new(FILE *file) {
+    fmt_stream_t stream;
+    stream.w = 0;
+    stream.ctx = file;
+    stream.out_ctype = fstream_outc;
+    stream.out_wchar = fstream_outw;
+    stream.out_char = fstream_outc;
+    return stream;
+}
+
+int vfprintf(FILE *restrict file, const char *restrict string, va_list va) {
+    fmt_stream_t stream = fstream_new(file);
+    return fmt(&stream, string, va);
+}
+
+int vprintf(const char *restrict string, va_list va) {
+    return vfprintf(stdout, string, va);
+}
+
+int fprintf(FILE *restrict file, const char *restrict string, ...) {
+    va_list va;
+    va_start(va, string);
+    int result = vfprintf(file, string, va);
+    va_end(va);
+    return result;
+}
+
+int printf(const char *restrict string, ...) {
+    va_list va;
+    va_start(va, string);
+    int result = vfprintf(stdout, string, va);
+    va_end(va);
+    return result;
+}
+
+// s(n)printf family
+
+struct str_slice_t typedef str_slice_t;
+struct str_slice_t {
+    char *str;
+    size_t max_size;
+    size_t written;
+};
+
+static inline int sstream_outc(void *ctx, char c) {
+    str_slice_t *slice = ctx;
+    if(slice->written+1 < slice->max_size) {
+        return -1;
+    }
+    slice->str[slice->written++] = c;
+    return 1;
+}
+
+static inline int sstream_outw(void *ctx, wchar c) {
+    str_slice_t *slice = ctx;
+    // TODO: utf8
+    if(slice->written+1 < slice->max_size) {
+        return -1;
+    }
+    slice->str[slice->written++] = c;
+    return 1;
+}
+
+static inline fmt_stream_t sstream_new(str_slice_t *slice) {
+    fmt_stream_t stream;
+    stream.w = 0;
+    stream.ctx = slice;
+    stream.out_ctype = sstream_outc;
+    stream.out_wchar = sstream_outw;
+    stream.out_char  = sstream_outc;
+    return stream;
+}
+
+int vsnprintf(char *restrict buf, size_t cbbuf, const char *restrict str, va_list va) {
+    str_slice_t slice;
+    slice.str = buf;
+    slice.max_size = cbbuf;
+    slice.written = 0;
+    fmt_stream_t stream = sstream_new(&slice);
+    return fmt(&stream, str, va);
+}
+
+int vsprintf(char *restrict buf, const char *restrict str, va_list va) {
+    str_slice_t slice;
+    slice.str = buf;
+    slice.max_size = SIZE_MAX;
+    slice.written = 0;
+    fmt_stream_t stream = sstream_new(&slice);
+    return fmt(&stream, str, va);
+}
+
+int snprintf(char *restrict buf, size_t cbbuf, const char *restrict str, ...) {
+    va_list va;
+    va_start(va, str);
+    int result = vsnprintf(buf, cbbuf, str, va);
+    va_end(va);
+    return result;
+}
+
+int sprintf(char *restrict buf, const char *restrict str, ...) {
+    va_list va;
+    va_start(va, str);
+    int result = vsprintf(buf, str, va);
+    va_end(va);
+    return result;
+}
diff --git a/src/fmt/fmt.h b/src/fmt/fmt.h
new file mode 100644
index 0000000..6d263c7
--- /dev/null
+++ b/src/fmt/fmt.h
@@ -0,0 +1,44 @@
+
+static inline int pfx(fmt_arg)(fmt_stream_t *stream, ctype const **strp, va_list va) {
+    ctype const *str = *strp; 
+    fmt_t fmt = {0};
+    if(!pfx(fmt_read)(str, &fmt, va)) {
+        return 0;
+    }
+    switch(*str) {
+        case 'i':
+        case 'u':
+        case 'b':
+        case 'o':
+        case 'd':
+        case 'x':
+        case 'X':
+        {
+            int base;
+            int sign;
+            u64 abs = pfx(fmt_int_arg)(stream, &fmt, &str, &sign, &base, va);
+            if(pfx(fmt_int)(stream, fmt, sign, abs, base) == -1) {
+                return -1;
+            }
+        } break;
+    }
+    *strp = str;
+    return 1;
+}
+
+static inline int pfx(fmt)(fmt_stream_t *stream, ctype const *str, va_list va) {
+    stream->w = 0;
+    while(*str) {
+        if(*str == '%') {
+            ++str;
+            int ok = pfx(fmt_arg)(stream, &str, va);
+            if(!ok) {
+                return -1;
+            }
+        }
+        else {
+            stream_out(stream, *str++);
+        }
+    }
+    return stream->w;
+}
diff --git a/src/fmt/fmt_stream.h b/src/fmt/fmt_stream.h
new file mode 100644
index 0000000..22e9a5d
--- /dev/null
+++ b/src/fmt/fmt_stream.h
@@ -0,0 +1,13 @@
+
+struct pfx(fmt_stream_t) typedef pfx(fmt_stream_t);
+struct pfx(fmt_stream_t) {
+    int w;
+    void *ctx;
+    int (*pfx(out_ctype))(void *ctx, ctype ch);
+    int (*pfx(out_wchar))(void *ctx, wchar ch);
+    int (*pfx(out_char)) (void *ctx, char  ch);
+};
+
+#define stream_out(s, ch)  if((s->w++, !s->out_ctype(s->ctx, ch))) return -1
+#define stream_outc(s, ch) if((s->w++, !s->out_char (s->ctx, ch))) return -1
+#define stream_outw(s, ch) if((s->w++, !s->out_wchar(s->ctx, ch))) return -1
diff --git a/src/fmt/fmt_string.h b/src/fmt/fmt_string.h
new file mode 100644
index 0000000..1c0eb8f
--- /dev/null
+++ b/src/fmt/fmt_string.h
@@ -0,0 +1,74 @@
+
+static inline int pfx(fmt_isdigit)(ctype ch) {
+    return '0' <= ch && ch <= '9';
+}
+
+static inline int pfx(fmt_atoi)(ctype const **sp, int *err) {
+    int i = 0;
+    ctype const *s = *sp;
+    while(pfx(fmt_isdigit(*s))) {
+        int d = *s-'0';
+        if(i > (INT_MAX - d)/10) {
+            *err = 1;
+            return 0;
+        }
+        i = 10*i + d;
+        ++s;
+    }
+    *sp = s;
+    return i;
+}
+
+static inline int pfx(fmt_read)(const ctype *str, fmt_t *fmt, va_list va) {
+    int flags = 0;
+    // Parse flag field
+    {
+        int isflag = 0;
+        do {
+            isflag = 1;
+            switch(*str) {
+                case '0': flags |= FLAG_ZERO;  break;
+                case '-': flags |= FLAG_LEFT;  break;
+                case '+': flags |= FLAG_PLUS;  break;
+                case ' ': flags |= FLAG_SPACE; break;
+                case '#': flags |= FLAG_HASH;  break;
+                default:  isflag = 0;
+            }
+            if(isflag) ++str;
+        } while(isflag);
+        // If '-' and '0' are together we just discard '0'
+        if(flags & FLAG_LEFT) flags &= ~FLAG_ZERO;
+    }
+    // Parse width field
+    int width = 0;
+    if(pfx(fmt_isdigit(*str))) {
+        int err = 0;
+        width = pfx(fmt_atoi(&str, &err));
+        if(err) return 0;
+    }
+    else if(*str == '*') {
+        ++str;
+        width = va_arg(va, int);
+        if(width < 0) {
+            width = -width;
+            flags |= FLAG_LEFT;
+        }
+    }
+    // If present, parse the precision field
+    int prec = 0;
+    if(*str == '.') {
+        flags |= FLAG_PREC;
+        ++str;
+        if(pfx(fmt_isdigit(*str))) {
+            int err = 0;
+            prec = pfx(fmt_atoi(&str, &err));
+            if(err) return -1;
+        }
+        else if(*str == '*') {
+            ++str;
+            prec = va_arg(va, int);
+            prec = (prec > 0? prec : 0);
+        }
+    }
+    return 1;
+}
diff --git a/src/fmt/ints.h b/src/fmt/ints.h
new file mode 100644
index 0000000..2a72d73
--- /dev/null
+++ b/src/fmt/ints.h
@@ -0,0 +1,150 @@
+
+static inline u64 pfx(fmt_int_arg)(
+    fmt_stream_t *stream,
+    fmt_t *fmt,
+    ctype const **strp,
+    int *signp,
+    int *basep,
+    va_list va
+) {
+    ctype const *str = *strp;
+    // Get integer properties
+    int base;
+    int is_signed;
+    switch(*str) {
+        case 'o': base = 8; break;
+        case 'b': base = 2; break;
+        case 'x':
+        case 'X': base = 16; break;
+        default:  base = 10;
+    }
+    switch(*str) {
+        case 'd': is_signed = 1; break;
+        case 'i': is_signed = 1; break;
+        default:  is_signed = 0;
+    }
+    if(*str == 'X') {
+        fmt->flags |= FLAG_UPPER;
+    }
+    // Discard some flags
+    if(base == 10) {
+        fmt->flags &= ~FLAG_HASH;
+    }
+    if(!is_signed) {
+        fmt->flags &= ~(FLAG_PLUS|FLAG_SPACE);
+    }
+    if(fmt->flags & FLAG_PREC) {
+        fmt->flags &= ~FLAG_ZERO;
+    }
+    // Parse sign and abs value of an integer
+    int sign = 0;
+    u64 abs_value = 0;
+    if(is_signed) {
+        i64 num;
+        if(fmt->flags & FLAG_LLONG) {
+            num = (i64)va_arg(va, intll);
+        }
+        else if(fmt->flags & FLAG_LONG) {
+            num = (i64)va_arg(va, intl);
+        }
+        else {
+            num = (i64)va_arg(va, int);
+        }
+        // Handle overflow on '-'
+        if(num == LLONG_MIN) {
+            sign = 1;
+            abs_value = (u64)LLONG_MAX + 1;
+        }
+        else {
+            sign = num >= 0?   0 :    1;
+            num = num >= 0? num : -num;
+            abs_value = (u64)num;
+        }
+    }
+    else {
+        if(fmt->flags & FLAG_LLONG) {
+            abs_value = (u64)va_arg(va, intull);
+        }
+        else if(fmt->flags & FLAG_LONG) {
+            abs_value = (u64)va_arg(va, intul);
+        }
+        else {
+            abs_value = (u64)va_arg(va, intu);
+        }
+    }
+    ++str;
+    *strp = str;
+    *basep = base;
+    *signp = sign;
+    return abs_value;
+}
+
+static inline int pfx(fmt_int)(
+    fmt_stream_t *stream,
+    fmt_t fmt,
+    int neg,
+    u64 value,
+    int base) {
+    // We'll Write digits into buf in reverse and then call _out_rbuf
+    int ndigits = 0;
+    ctype digits[64] = {0};
+    // Remove hash flag for 0 values
+    if(value == 0) fmt.flags &= ~FLAG_HASH;
+    // Write digits to buffer in reverse (starting from least significant)
+    do {
+        int d = (int)(value%base);
+        value /= base;
+        if(d < 10)
+             d += '0';
+        else if(fmt.flags & FLAG_UPPER)
+             d += 'A' - 10;
+        else d += 'a' - 10;
+        digits[ndigits++] = d;
+    } while(value);
+    // Figure out the length of the prefix (part of number before digit stirng)
+    int pref_len = 0;
+    if(fmt.flags & FLAG_HASH)       pref_len = base == 8? 1 : 2;
+    else if(neg)                pref_len = 1;
+    else if(fmt.flags & FLAG_PLUS)  pref_len = 1;
+    else if(fmt.flags & FLAG_SPACE) pref_len = 1;
+    if(ndigits > fmt.prec) fmt.prec = ndigits;
+    int num_len = pref_len + fmt.prec;
+    int pad_len = fmt.width - num_len;
+    if(!(fmt.flags & FLAG_LEFT)) {
+        ctype pad_ch = ' ';
+        if(fmt.flags & FLAG_ZERO) pad_ch = '0';
+        while(pad_len-- > 0) {
+            stream_out(stream, pad_ch);
+        }
+    }
+    // Print width left-pad if it's made out of space
+    if(!(fmt.flags & FLAG_LEFT) && !(fmt.flags & FLAG_ZERO)) while(pad_len-- > 0) {
+        stream_out(stream, ' ');
+    }
+    // Print prefix
+    if(fmt.flags & FLAG_HASH) {
+        stream_out(stream, '0');
+        if(base == 16)     { stream_out(stream, 'x'); }
+        else if(base == 2) { stream_out(stream, 'b'); }
+    }
+    else if(neg)                { stream_out(stream, '-'); }
+    else if(fmt.flags & FLAG_PLUS)  { stream_out(stream, '+'); }
+    else if(fmt.flags & FLAG_SPACE) { stream_out(stream, ' '); }
+    // Print width left-pad if it's made out of zero
+    if(!(fmt.flags & FLAG_LEFT) && (fmt.flags & FLAG_ZERO)) while(pad_len-- > 0) {
+        stream_out(stream, '0');
+    }
+    // Print zero-pad due to precision
+    for(int i = ndigits; i < fmt.prec; ++i) {
+        stream_out(stream, '0');
+    }
+    // Output buffer in reverse
+    if(ndigits) while(ndigits--) {
+        stream_out(stream, digits[ndigits]);
+    }
+    // Print right-pad
+    if(fmt.flags & FLAG_LEFT) while(pad_len-- > 0) {
+        stream_out(stream, ' ');
+    }
+    return stream->w;
+}
diff --git a/test.cmd b/test.cmd
deleted file mode 100644
index c543659..0000000
--- a/test.cmd
+++ /dev/null
@@ -1,2 +0,0 @@
-
-clang -std=c11 test\%1 utf8.obj -Iinc -g -lciabatta.lib -nostdlib -fstack-protector
\ No newline at end of file
diff --git a/test/printf.c b/test/printf.c
new file mode 100644
index 0000000..7910aaf
--- /dev/null
+++ b/test/printf.c
@@ -0,0 +1,12 @@
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+
+int main() {
+    printf("%i\n", INT_MAX);
+    printf("%i\n", INT_MIN);
+    printf("%x\n", UINT_MAX);
+    printf("%x\n", 0);
+    return 0;
+}