diff --git a/audio/out/ao_alsa.c b/audio/out/ao_alsa.c
index 25a051fee8..cd46e52806 100644
--- a/audio/out/ao_alsa.c
+++ b/audio/out/ao_alsa.c
@@ -31,7 +31,6 @@
 #include <sys/time.h>
 #include <stdlib.h>
 #include <stdarg.h>
-#include <ctype.h>
 #include <math.h>
 #include <string.h>
 
diff --git a/audio/out/ao_coreaudio_utils.c b/audio/out/ao_coreaudio_utils.c
index 11f89422ff..052f63d608 100644
--- a/audio/out/ao_coreaudio_utils.c
+++ b/audio/out/ao_coreaudio_utils.c
@@ -30,7 +30,7 @@ char *fourcc_repr(void *talloc_ctx, uint32_t code)
 {
     // Extract FourCC letters from the uint32_t and finde out if it's a valid
     // code that is made of letters.
-    char fcc[4] = {
+    unsigned char fcc[4] = {
         (code >> 24) & 0xFF,
         (code >> 16) & 0xFF,
         (code >> 8)  & 0xFF,
@@ -39,7 +39,7 @@ char *fourcc_repr(void *talloc_ctx, uint32_t code)
 
     bool valid_fourcc = true;
     for (int i = 0; i < 4; i++)
-        if (!isprint(fcc[i]))
+        if (fcc[i] >= 32 && fcc[i] < 128)
             valid_fourcc = false;
 
     char *repr;
diff --git a/bstr/bstr.c b/bstr/bstr.c
index 964934a100..de8f285161 100644
--- a/bstr/bstr.c
+++ b/bstr/bstr.c
@@ -18,7 +18,6 @@
 
 #include <string.h>
 #include <assert.h>
-#include <ctype.h>
 #include <stdarg.h>
 #include <stdint.h>
 #include <stdlib.h>
@@ -28,6 +27,7 @@
 #include "talloc.h"
 
 #include "common/common.h"
+#include "misc/ctype.h"
 #include "bstr/bstr.h"
 
 int bstrcmp(struct bstr str1, struct bstr str2)
@@ -104,7 +104,7 @@ int bstr_find(struct bstr haystack, struct bstr needle)
 
 struct bstr bstr_lstrip(struct bstr str)
 {
-    while (str.len && isspace(*str.start)) {
+    while (str.len && mp_isspace(*str.start)) {
         str.start++;
         str.len--;
     }
@@ -114,7 +114,7 @@ struct bstr bstr_lstrip(struct bstr str)
 struct bstr bstr_strip(struct bstr str)
 {
     str = bstr_lstrip(str);
-    while (str.len && isspace(str.start[str.len - 1]))
+    while (str.len && mp_isspace(str.start[str.len - 1]))
         str.len--;
     return str;
 }
@@ -242,7 +242,7 @@ bool bstr_eatstart(struct bstr *s, struct bstr prefix)
 void bstr_lower(struct bstr str)
 {
     for (int i = 0; i < str.len; i++)
-        str.start[i] = tolower(str.start[i]);
+        str.start[i] = mp_tolower(str.start[i]);
 }
 
 int bstr_sscanf(struct bstr str, const char *format, ...)
diff --git a/demux/demux_mkv.c b/demux/demux_mkv.c
index e3991372f9..25591cd60a 100644
--- a/demux/demux_mkv.c
+++ b/demux/demux_mkv.c
@@ -23,7 +23,6 @@
 
 #include <stdlib.h>
 #include <stdio.h>
-#include <ctype.h>
 #include <inttypes.h>
 #include <stdbool.h>
 #include <assert.h>
diff --git a/demux/demux_subreader.c b/demux/demux_subreader.c
index d3a792c9d2..6eb58f0033 100644
--- a/demux/demux_subreader.c
+++ b/demux/demux_subreader.c
@@ -26,7 +26,6 @@
 #include <string.h>
 #include <sys/types.h>
 #include <dirent.h>
-#include <ctype.h>
 
 #include <libavutil/common.h>
 #include <libavutil/avstring.h>
diff --git a/demux/mf.c b/demux/mf.c
index 5edc98043a..d687c3cb19 100644
--- a/demux/mf.c
+++ b/demux/mf.c
@@ -16,7 +16,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -30,6 +29,7 @@
 #include "talloc.h"
 #include "common/msg.h"
 #include "stream/stream.h"
+#include "misc/ctype.h"
 #include "options/path.h"
 
 #include "mf.h"
@@ -55,7 +55,7 @@ mf_t *open_mf_pattern(void *talloc_ctx, struct mp_log *log, char *filename)
             while (fgets(fname, 512, lst_f)) {
                 /* remove spaces from end of fname */
                 char *t = fname + strlen(fname) - 1;
-                while (t > fname && isspace((unsigned char)*t))
+                while (t > fname && mp_isspace(*t))
                     *(t--) = 0;
                 if (!mp_path_exists(fname)) {
                     mp_verbose(log, "file not found: '%s'\n", fname);
diff --git a/input/input.c b/input/input.c
index 212a6ff92d..983cb84fe3 100644
--- a/input/input.c
+++ b/input/input.c
@@ -28,7 +28,6 @@
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <fcntl.h>
-#include <ctype.h>
 #include <pthread.h>
 #include <assert.h>
 
diff --git a/misc/ctype.h b/misc/ctype.h
new file mode 100644
index 0000000000..cbff799285
--- /dev/null
+++ b/misc/ctype.h
@@ -0,0 +1,19 @@
+#ifndef MP_CTYPE_H_
+#define MP_CTYPE_H_
+
+// Roughly follows C semantics, but doesn't account for EOF, allows char as
+// parameter, and is locale independent (always uses "C" locale).
+
+static inline int mp_isprint(char c) { return (unsigned char)c >= 32; }
+static inline int mp_isspace(char c) { return c == ' ' || c == '\f' || c == '\n' ||
+                                              c == '\r' || c == '\t' || c =='\v'; }
+static inline int mp_isupper(char c) { return c >= 'A' && c <= 'Z'; }
+static inline int mp_islower(char c) { return c >= 'a' && c <= 'z'; }
+static inline int mp_isdigit(char c) { return c >= '0' && c <= '9'; }
+static inline int mp_isalpha(char c) { return mp_isupper(c) || mp_islower(c); }
+static inline int mp_isalnum(char c) { return mp_isalpha(c) || mp_isdigit(c); }
+
+static inline char mp_tolower(char c) { return mp_isupper(c) ? c - 'A' + 'a' : c; }
+static inline char mp_toupper(char c) { return mp_islower(c) ? c - 'a' + 'A' : c; }
+
+#endif
diff --git a/options/m_option.c b/options/m_option.c
index 3baaaa6762..52dd18b9d2 100644
--- a/options/m_option.c
+++ b/options/m_option.c
@@ -29,7 +29,6 @@
 #include <limits.h>
 #include <inttypes.h>
 #include <unistd.h>
-#include <ctype.h>
 #include <assert.h>
 
 #include <libavutil/common.h>
diff --git a/options/parse_configfile.c b/options/parse_configfile.c
index 1e12a5c47f..112a26b115 100644
--- a/options/parse_configfile.c
+++ b/options/parse_configfile.c
@@ -22,13 +22,13 @@
 #include <stdlib.h>
 #include <string.h>
 #include <errno.h>
-#include <ctype.h>
 #include <assert.h>
 
 #include "osdep/io.h"
 
 #include "parse_configfile.h"
 #include "common/msg.h"
+#include "misc/ctype.h"
 #include "m_option.h"
 #include "m_config.h"
 
@@ -95,7 +95,7 @@ int m_config_parse_config_file(m_config_t *config, const char *conffile,
         line_pos = 0;
 
         /* skip whitespaces */
-        while (isspace(line[line_pos]))
+        while (mp_isspace(line[line_pos]))
             ++line_pos;
 
         /* EOL / comment */
@@ -103,7 +103,7 @@ int m_config_parse_config_file(m_config_t *config, const char *conffile,
             continue;
 
         /* read option. */
-        for (opt_pos = 0; isprint(line[line_pos]) &&
+        for (opt_pos = 0; mp_isprint(line[line_pos]) &&
              line[line_pos] != ' ' &&
              line[line_pos] != '#' &&
              line[line_pos] != '='; /* NOTHING */) {
@@ -133,7 +133,7 @@ int m_config_parse_config_file(m_config_t *config, const char *conffile,
         }
 
         /* skip whitespaces */
-        while (isspace(line[line_pos]))
+        while (mp_isspace(line[line_pos]))
             ++line_pos;
 
         param_pos = 0;
@@ -145,7 +145,7 @@ int m_config_parse_config_file(m_config_t *config, const char *conffile,
             param_set = true;
 
             /* whitespaces... */
-            while (isspace(line[line_pos]))
+            while (mp_isspace(line[line_pos]))
                 ++line_pos;
 
             /* read the parameter */
@@ -187,8 +187,8 @@ int m_config_parse_config_file(m_config_t *config, const char *conffile,
                 }
             }
 
-            for (param_pos = 0; isprint(line[line_pos])
-                    && !isspace(line[line_pos])
+            for (param_pos = 0; mp_isprint(line[line_pos])
+                    && !mp_isspace(line[line_pos])
                     && line[line_pos] != '#'; /* NOTHING */) {
                 param[param_pos++] = line[line_pos++];
                 if (param_pos >= MAX_PARAM_LEN) {
@@ -202,7 +202,7 @@ int m_config_parse_config_file(m_config_t *config, const char *conffile,
 
         param_done:
 
-            while (isspace(line[line_pos]))
+            while (mp_isspace(line[line_pos]))
                 ++line_pos;
         }
         param[param_pos] = '\0';
diff --git a/player/configfiles.c b/player/configfiles.c
index dab26b9df2..d1c79c9c9d 100644
--- a/player/configfiles.c
+++ b/player/configfiles.c
@@ -22,7 +22,6 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
-#include <ctype.h>
 
 #include <libavutil/md5.h>
 
@@ -34,6 +33,7 @@
 #include "common/global.h"
 #include "common/encode.h"
 #include "common/msg.h"
+#include "misc/ctype.h"
 #include "options/path.h"
 #include "options/m_config.h"
 #include "options/parse_configfile.h"
@@ -267,7 +267,7 @@ static bool needs_config_quoting(const char *s)
 {
     for (int i = 0; s && s[i]; i++) {
         unsigned char c = s[i];
-        if (!isprint(c) || isspace(c) || c == '#' || c == '\'' || c == '"')
+        if (!mp_isprint(c) || mp_isspace(c) || c == '#' || c == '\'' || c == '"')
             return true;
     }
     return false;
diff --git a/player/main.c b/player/main.c
index 0a18df1a4e..aebfa06fb1 100644
--- a/player/main.c
+++ b/player/main.c
@@ -21,7 +21,6 @@
 #include <stdbool.h>
 #include <math.h>
 #include <assert.h>
-#include <ctype.h>
 #include <string.h>
 #include <pthread.h>
 
diff --git a/player/timeline/tl_cue.c b/player/timeline/tl_cue.c
index 6731ab4058..d5e8b08164 100644
--- a/player/timeline/tl_cue.c
+++ b/player/timeline/tl_cue.c
@@ -20,7 +20,6 @@
 #include <stdlib.h>
 #include <stdbool.h>
 #include <inttypes.h>
-#include <ctype.h>
 
 #include "talloc.h"
 
diff --git a/player/timeline/tl_mpv_edl.c b/player/timeline/tl_mpv_edl.c
index aba9738d53..78fc8b7cdc 100644
--- a/player/timeline/tl_mpv_edl.c
+++ b/player/timeline/tl_mpv_edl.c
@@ -19,7 +19,6 @@
 #include <stdlib.h>
 #include <stdbool.h>
 #include <inttypes.h>
-#include <ctype.h>
 #include <math.h>
 
 #include "talloc.h"
diff --git a/stream/dvb_tune.c b/stream/dvb_tune.c
index 7065a77aa3..056592bceb 100644
--- a/stream/dvb_tune.c
+++ b/stream/dvb_tune.c
@@ -25,7 +25,6 @@
 
 #include <stdio.h>
 #include <stdlib.h>
-#include <ctype.h>
 #include <sys/ioctl.h>
 #include <poll.h>
 #include <unistd.h>
diff --git a/stream/stream_dvb.c b/stream/stream_dvb.c
index d6ebddb944..87b2495a51 100644
--- a/stream/stream_dvb.c
+++ b/stream/stream_dvb.c
@@ -34,7 +34,6 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <ctype.h>
 #include <sys/ioctl.h>
 #include <sys/time.h>
 #include <poll.h>
@@ -45,6 +44,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 #include <libavutil/avstring.h>
 
 #include "osdep/io.h"
+#include "misc/ctype.h"
 
 #include "stream.h"
 #include "options/m_config.h"
@@ -177,7 +177,7 @@ static dvb_channels_list *dvb_get_channels(struct mp_log *log, char *filename, i
                 {
                         fields = sscanf(&line[k], sat_conf,
                                 &ptr->freq, &ptr->pol, &ptr->diseqc, &ptr->srate, vpid_str, apid_str);
-                        ptr->pol = toupper(ptr->pol);
+                        ptr->pol = mp_toupper(ptr->pol);
                         ptr->freq *=  1000UL;
                         ptr->srate *=  1000UL;
                         ptr->tone = -1;
diff --git a/stream/stream_dvd.c b/stream/stream_dvd.c
index 2195189c42..9773e14fa1 100644
--- a/stream/stream_dvd.c
+++ b/stream/stream_dvd.c
@@ -18,7 +18,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/stream/stream_pvr.c b/stream/stream_pvr.c
index db355131b1..217a27849a 100644
--- a/stream/stream_pvr.c
+++ b/stream/stream_pvr.c
@@ -30,7 +30,6 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
-#include <ctype.h>
 #include <sys/time.h>
 #include <errno.h>
 #include <sys/ioctl.h>
diff --git a/stream/tv.c b/stream/tv.c
index 17b1f9ecb9..726b7d0880 100644
--- a/stream/tv.c
+++ b/stream/tv.c
@@ -29,7 +29,6 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
-#include <ctype.h>
 #include <sys/time.h>
 #include <assert.h>
 #include <libavutil/avstring.h>
@@ -38,6 +37,7 @@
 
 
 #include "common/msg.h"
+#include "misc/ctype.h"
 
 #include "options/m_option.h"
 #include "options/m_config.h"
@@ -628,7 +628,7 @@ static int open_tv(tvi_handle_t *tvh)
         int channel = 0;
         if (tvh->tv_param->channel)
          {
-           if (isdigit(*tvh->tv_param->channel))
+           if (mp_isdigit(*tvh->tv_param->channel))
                 /* if tvh->tv_param->channel begins with a digit interpret it as a number */
                 channel = atoi(tvh->tv_param->channel);
            else
diff --git a/sub/find_subfiles.c b/sub/find_subfiles.c
index 9313bf379d..ade267cfa6 100644
--- a/sub/find_subfiles.c
+++ b/sub/find_subfiles.c
@@ -1,16 +1,16 @@
 #include <dirent.h>
 #include <string.h>
 #include <stdlib.h>
-#include <ctype.h>
 #include <assert.h>
 
 #include "osdep/io.h"
 
+#include "common/common.h"
 #include "common/global.h"
 #include "common/msg.h"
+#include "misc/ctype.h"
 #include "options/options.h"
 #include "options/path.h"
-#include "common/common.h"
 #include "sub/find_subfiles.h"
 
 static const char *const sub_exts[] = {"utf", "utf8", "utf-8", "idx", "sub", "srt",
@@ -75,7 +75,7 @@ static struct bstr guess_lang_from_filename(struct bstr name)
 
     if (name.start[i] == ')' || name.start[i] == ']')
         i--;
-    while (i >= 0 && isalpha(name.start[i])) {
+    while (i >= 0 && mp_isalpha(name.start[i])) {
         n++;
         if (n > 3)
             return (struct bstr){NULL, 0};
diff --git a/sub/sd_microdvd.c b/sub/sd_microdvd.c
index 6e6a9c31a8..5de9a1814b 100644
--- a/sub/sd_microdvd.c
+++ b/sub/sd_microdvd.c
@@ -24,7 +24,6 @@
 #include <stdio.h>
 #include <stdarg.h>
 #include <stdbool.h>
-#include <ctype.h>
 #include <libavutil/common.h>
 
 #include "common/msg.h"
diff --git a/sub/sd_srt.c b/sub/sd_srt.c
index 733a27d0f4..0ca807f312 100644
--- a/sub/sd_srt.c
+++ b/sub/sd_srt.c
@@ -24,11 +24,11 @@
 #include <stdio.h>
 #include <stdarg.h>
 #include <stdbool.h>
-#include <ctype.h>
-#include <libavutil/common.h>
 
+#include "common/common.h"
 #include "common/msg.h"
 #include "bstr/bstr.h"
+#include "misc/ctype.h"
 #include "sd.h"
 
 struct line {
@@ -259,7 +259,7 @@ static int read_attr(char **s, struct bstr *attr, struct bstr *val)
     attr->start = *s;
     attr->len = eq - *s;
     for (int i = 0; i < attr->len; i++)
-        if (!isalnum(attr->start[i]))
+        if (!mp_isalnum(attr->start[i]))
             return -1;
     val->start = eq + 1;
     bool quoted = val->start[0] == '"';
@@ -290,7 +290,7 @@ static void convert_subrip(struct sd *sd, const char *orig,
     while (*line && new_line.len < new_line.bufsize - 1) {
         char *orig_line = line;
 
-        for (int i = 0; i < FF_ARRAY_ELEMS(subrip_basic_tags); i++) {
+        for (int i = 0; i < MP_ARRAY_SIZE(subrip_basic_tags); i++) {
             const struct tag_conv *tag = &subrip_basic_tags[i];
             int from_len = strlen(tag->from);
             if (strncmp(line, tag->from, from_len) == 0) {
@@ -331,7 +331,7 @@ static void convert_subrip(struct sd *sd, const char *orig,
                 }
             }
         } else if (strncmp(line, "<font ", 6) == 0
-                   && sp + 1 < FF_ARRAY_ELEMS(font_stack)) {
+                   && sp + 1 < MP_ARRAY_SIZE(font_stack)) {
             /* Opening font tag */
             char *potential_font_tag_start = line;
             int len_backup = new_line.len;
@@ -360,7 +360,7 @@ static void convert_subrip(struct sd *sd, const char *orig,
                     int found = 0;
 
                     // Try to lookup the string in standard web colors
-                    for (int i = 0; i < FF_ARRAY_ELEMS(subrip_web_colors); i++) {
+                    for (int i = 0; i < MP_ARRAY_SIZE(subrip_web_colors); i++) {
                         char *color = subrip_web_colors[i].s;
                         if (bstrcasecmp(val, bstr0(color)) == 0) {
                             uint32_t xcolor = subrip_web_colors[i].v;
diff --git a/video/out/gl_common.c b/video/out/gl_common.c
index 131a35daaf..f9af3f32af 100644
--- a/video/out/gl_common.c
+++ b/video/out/gl_common.c
@@ -36,7 +36,6 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <ctype.h>
 #include <stdbool.h>
 #include <math.h>
 #include <assert.h>
diff --git a/video/out/pnm_loader.c b/video/out/pnm_loader.c
index 048461e51f..70afe0fa23 100644
--- a/video/out/pnm_loader.c
+++ b/video/out/pnm_loader.c
@@ -33,7 +33,7 @@
 #include <stdlib.h>
 #include <stdint.h>
 #include <stdio.h>
-#include <ctype.h>
+#include "misc/ctype.h"
 #include "pnm_loader.h"
 
 /**
@@ -48,7 +48,7 @@ static void ppm_skip(FILE *f) {
       comment = 1;
     if (c == '\n')
       comment = 0;
-  } while (c != EOF && (isspace(c) || comment));
+  } while (c != EOF && (mp_isspace(c) || comment));
   if (c != EOF)
     ungetc(c, f);
 }
@@ -77,7 +77,7 @@ uint8_t *read_pnm(FILE *f, int *width, int *height,
   if (fscanf(f, "%u", &m) != 1)
     return NULL;
   val = fgetc(f);
-  if (!isspace(val))
+  if (!mp_isspace(val))
     return NULL;
   if (w > MAXDIM || h > MAXDIM)
     return NULL;
diff --git a/video/out/vo_opengl_old.c b/video/out/vo_opengl_old.c
index d9c7e8baed..87ba48068a 100644
--- a/video/out/vo_opengl_old.c
+++ b/video/out/vo_opengl_old.c
@@ -28,12 +28,12 @@
 #include <string.h>
 #include <math.h>
 #include <stdbool.h>
-#include <ctype.h>
 #include <assert.h>
 
 #include "config.h"
 #include "talloc.h"
 #include "common/msg.h"
+#include "misc/ctype.h"
 #include "options/m_option.h"
 #include "vo.h"
 #include "video/vfcap.h"
@@ -538,7 +538,7 @@ static void replace_var_str(char **text, const char *name, const char *replace)
         nextvar += namelen;
         // try not to replace prefixes of other vars (e.g. $foo vs. $foo_bar)
         char term = nextvar[0];
-        if (isalnum(term) || term == '_')
+        if (mp_isalnum(term) || term == '_')
             continue;
         int prelength = until - *text;
         int postlength = nextvar - *text;