diff --git a/INSTALL.md b/INSTALL.md
index a29148a..a99e50c 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -12,7 +12,7 @@ this notice are preserved. This file is offered as-is, without any warranty.
 
 This is the recommended way to use this library.
 
-Copy [ctlseqs.h](src/ctlseqs.h) and [ctlseqs.c](src/ctlseqs.c) to your project and build it alongside with other code. Requires an ISO C99 and POSIX.1-2008 compliant C implementation.
+Copy [ctlseqs.h](src/ctlseqs.h) and [ctlseqs.c](src/ctlseqs.c) to your project and build it alongside with other code. Requires an ISO C99 and POSIX.1-2001 compliant C implementation.
 
 ## Build and Install From Source
 
diff --git a/configure.ac b/configure.ac
index 12aacdf..d770e38 100644
--- a/configure.ac
+++ b/configure.ac
@@ -41,7 +41,7 @@ AC_TYPE_SIZE_T
 AC_TYPE_SSIZE_T
 
 # Checks for library functions.
-AC_CHECK_FUNCS([dprintf memset strtoul])
+AC_CHECK_FUNCS([memset strtoul])
 
 # Specify libtool library version.
 m4_define([CTLSEQS_LT_CURRENT], [0])
@@ -49,8 +49,5 @@ m4_define([CTLSEQS_LT_REVISION], [0])
 m4_define([CTLSEQS_LT_AGE], [0])
 AC_SUBST([CTLSEQS_LT_VERSION], [CTLSEQS_LT_CURRENT:CTLSEQS_LT_REVISION:CTLSEQS_LT_AGE])
 
-# Assume that POSIX.1-2008 is supported.
-AC_DEFINE([_POSIX_C_SOURCE], [200809L], [Feature test macro for POSIX.1-2008])
-
 AC_CONFIG_FILES([Makefile doc/Makefile man/Makefile src/Makefile tests/Makefile examples/Makefile])
 AC_OUTPUT
diff --git a/examples/sixdraw.c b/examples/sixdraw.c
index 1b39340..385aac7 100644
--- a/examples/sixdraw.c
+++ b/examples/sixdraw.c
@@ -63,6 +63,8 @@ struct sixdraw_ctx {
     struct termios          termios;
     union ctlseqs_value     result[64];
     char const             *prog_name;
+    FILE*                   out_file;
+    FILE*                   err_file;
     struct ctlseqs_matcher *matcher;
     struct ctlseqs_reader  *reader;
     bool                    has_termios;
@@ -90,7 +92,7 @@ print_error(struct sixdraw_ctx const *ctx, char const *format, ...)
     va_start(args, format);
     vsnprintf(msg, 1024, format, args);
     va_end(args);
-    dprintf(ctx->out_fd, "%s: [error] %s.\n", ctx->prog_name, msg);
+    fprintf(ctx->err_file, "%s: [error] %s.\n", ctx->prog_name, msg);
 }
 
 static void
@@ -101,20 +103,20 @@ terminate(struct sixdraw_ctx *ctx)
 
     // Restore cursor status.
     if (ctx->hide_cursor) {
-        dprintf(ctx->out_fd, CTLSEQS_DECSET("%d"), DECTCEM);
+        fprintf(ctx->out_file, CTLSEQS_DECSET("%d"), DECTCEM);
     }
 
     // Restore normal screen buffer.
     if (ctx->alt_scrbuf) {
-        dprintf(ctx->out_fd, CTLSEQS_DECRST("%d"), ALT_SCRBUF);
+        fprintf(ctx->out_file, CTLSEQS_DECRST("%d"), ALT_SCRBUF);
     }
 
     // Restore original mouse modes.
     if (ctx->btnev_tracking) {
-        dprintf(ctx->out_fd, CTLSEQS_DECRST("%d"), BTN_EVENT_TRACKING);
+        fprintf(ctx->out_file, CTLSEQS_DECRST("%d"), BTN_EVENT_TRACKING);
     }
     if (ctx->sgr_pixelmode) {
-        dprintf(ctx->out_fd, CTLSEQS_DECRST("%d"), SGR_MOUSE_PIXELMODE);
+        fprintf(ctx->out_file, CTLSEQS_DECRST("%d"), SGR_MOUSE_PIXELMODE);
     }
 
     // Restore original terminal modes.
@@ -148,7 +150,7 @@ decrqm(struct sixdraw_ctx *ctx, unsigned mode, char const *name)
 {
     ssize_t retval;
     union ctlseqs_value *result = ctx->result;
-    dprintf(ctx->out_fd, CTLSEQS_DECRQM("%d"), mode);
+    fprintf(ctx->out_file, CTLSEQS_DECRQM("%d"), mode);
     do {
         retval = ctlseqs_read(ctx->reader, ctx->matcher, ctx->timeout);
     } while (retval == CTLSEQS_PARTIAL);
@@ -173,7 +175,7 @@ print_sixel_dot(struct sixdraw_ctx *ctx, unsigned x, unsigned y)
     // Move cursor.
     unsigned row = y / ctx->ch_height + 1;
     unsigned col = x / ctx->ch_width + 1;
-    dprintf(ctx->out_fd, CTLSEQS_CUP("%d", "%d"), row, col);
+    fprintf(ctx->out_file, CTLSEQS_CUP("%d", "%d"), row, col);
 
     // Build sixel sequence.
     row = y % ctx->ch_height;
@@ -182,13 +184,7 @@ print_sixel_dot(struct sixdraw_ctx *ctx, unsigned x, unsigned y)
     seq_size += sprintf(sixel_seq + seq_size, "%.*s!%u?%c" CTLSEQS_ST,
         row / 6, "------------------------", col, (1 << row % 6) + 0x3F);
 
-    // Output sixel sequence.
-    for (ssize_t nbytes; seq_size > 0; seq_size -= nbytes) {
-        nbytes = write(ctx->out_fd, sixel_seq, seq_size);
-        if (nbytes < 0) {
-            break;
-        }
-    }
+    fwrite(sixel_seq, seq_size, 1, ctx->out_file);
 }
 
 static bool
@@ -196,6 +192,8 @@ init(struct sixdraw_ctx *ctx, int argc, char **argv)
 {
     *ctx = (struct sixdraw_ctx) {
         .prog_name  = argc > 0 ? argv[0] : "sixdraw",
+        .out_file   = stdout,
+        .err_file   = stderr,
         .in_fd      = STDIN_FILENO,
         .out_fd     = STDOUT_FILENO,
         .timeout    = DEFAULT_TIMEOUT_MILLIS,
@@ -281,7 +279,7 @@ prepare(struct sixdraw_ctx *ctx)
     }
     ctx->has_termios = true;
 
-    // Set STDIN flags to nonblocking.
+    // Set STDIN flags to nonblocking, and disable output buffering.
     int flags = fcntl(ctx->in_fd, F_GETFL);
     if (flags == -1) {
         print_error(ctx, "failed to get file status flags");
@@ -291,6 +289,10 @@ prepare(struct sixdraw_ctx *ctx)
         print_error(ctx, "failed to set file status flags");
         return false;
     }
+    if (setvbuf(stdout, NULL, _IONBF, 0) != 0) {
+        print_error(ctx, "failed to disable output buffering");
+        return false;
+    }
 
     // Get initial terminal window size.
     if (!get_winsize(ctx)) {
@@ -298,7 +300,7 @@ prepare(struct sixdraw_ctx *ctx)
     }
 
     // Check terminal support for sixel graphics and DEC locator.
-    dprintf(ctx->out_fd, CTLSEQS_PRIMARY_DA());
+    fprintf(ctx->out_file, CTLSEQS_PRIMARY_DA());
     ssize_t retval;
     do {
         retval = ctlseqs_read(ctx->reader, ctx->matcher, ctx->timeout);
@@ -325,16 +327,7 @@ prepare(struct sixdraw_ctx *ctx)
     }
     ctx->hide_cursor = result[1].num == DECRQM_SET;
     if (ctx->hide_cursor) {
-        dprintf(ctx->out_fd, CTLSEQS_DECRST("%d"), DECTCEM);
-    }
-
-    // Switch to alternate screen buffer.
-    if (!decrqm(ctx, ALT_SCRBUF, "screen buffer")) {
-        return false;
-    }
-    ctx->alt_scrbuf = result[1].num == DECRQM_RST;
-    if (ctx->alt_scrbuf) {
-        dprintf(ctx->out_fd, CTLSEQS_DECSET("%d"), ALT_SCRBUF);
+        fprintf(ctx->out_file, CTLSEQS_DECRST("%d"), DECTCEM);
     }
 
     // Enable button event tracking mode.
@@ -343,7 +336,7 @@ prepare(struct sixdraw_ctx *ctx)
     }
     ctx->btnev_tracking = result[1].num == DECRQM_RST;
     if (ctx->btnev_tracking) {
-        dprintf(ctx->out_fd, CTLSEQS_DECSET("%d"), BTN_EVENT_TRACKING);
+        fprintf(ctx->out_file, CTLSEQS_DECSET("%d"), BTN_EVENT_TRACKING);
     }
 
     // Enable SGR mouse pixel mode.
@@ -352,7 +345,16 @@ prepare(struct sixdraw_ctx *ctx)
     }
     ctx->sgr_pixelmode = result[1].num == DECRQM_RST;
     if (ctx->sgr_pixelmode) {
-        dprintf(ctx->out_fd, CTLSEQS_DECSET("%d"), SGR_MOUSE_PIXELMODE);
+        fprintf(ctx->out_file, CTLSEQS_DECSET("%d"), SGR_MOUSE_PIXELMODE);
+    }
+
+    // Switch to alternate screen buffer.
+    if (!decrqm(ctx, ALT_SCRBUF, "screen buffer")) {
+        return false;
+    }
+    ctx->alt_scrbuf = result[1].num == DECRQM_RST;
+    if (ctx->alt_scrbuf) {
+        fprintf(ctx->out_file, CTLSEQS_DECSET("%d"), ALT_SCRBUF);
     }
 
     // Build the immutable part of sixel sequence.
@@ -367,9 +369,9 @@ prepare(struct sixdraw_ctx *ctx)
 static bool
 draw(struct sixdraw_ctx *ctx)
 {
-    dprintf(ctx->out_fd, CTLSEQS_CUP("%d", "1") "Canvas size: %ux%u. Line color: #%06X.",
+    fprintf(ctx->out_file, CTLSEQS_CUP("%d", "1") "Canvas size: %ux%u. Line color: #%06X.",
         ctx->rows - 1, ctx->canvas_width, ctx->canvas_height, ctx->line_color);
-    dprintf(ctx->out_fd, CTLSEQS_CUP("%d", "1") "Usage: Draw with mouse. Press Ctrl+C to exit.", ctx->rows);
+    fprintf(ctx->out_file, CTLSEQS_CUP("%d", "1") "Usage: Draw with mouse. Press Ctrl+C to exit.", ctx->rows);
 
     union ctlseqs_value *result = ctx->result;
     while (true) {
diff --git a/tests/tcsgrep.c b/tests/tcsgrep.c
index f26047d..bfff391 100644
--- a/tests/tcsgrep.c
+++ b/tests/tcsgrep.c
@@ -73,7 +73,7 @@ struct tcsgrep_ctx {
 static inline void
 print_error(struct tcsgrep_ctx const *ctx, char const *msg)
 {
-    dprintf(STDERR_FILENO, "%s: [error] %s.\n", ctx->prog_name, msg);
+    fprintf(stderr, "%s: [error] %s.\n", ctx->prog_name, msg);
 }
 
 static inline bool