diff --git a/avprobe.c b/avprobe.c
index 38b74a3bae..2f15d5ce2a 100644
--- a/avprobe.c
+++ b/avprobe.c
@@ -23,6 +23,7 @@
 
 #include "libavformat/avformat.h"
 #include "libavcodec/avcodec.h"
+#include "libavutil/avstring.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "libavutil/dict.h"
@@ -302,7 +303,7 @@ static void old_print_object_header(const char *name)
 
     str = p = av_strdup(name);
     while (*p) {
-        *p = toupper(*p);
+        *p = av_toupper(*p);
         p++;
     }
 
@@ -319,7 +320,7 @@ static void old_print_object_footer(const char *name)
 
     str = p = av_strdup(name);
     while (*p) {
-        *p = toupper(*p);
+        *p = av_toupper(*p);
         p++;
     }
 
diff --git a/avserver.c b/avserver.c
index ad7bc78f0c..2ab19d0bb8 100644
--- a/avserver.c
+++ b/avserver.c
@@ -1113,7 +1113,7 @@ static int extract_rates(char *rates, int ratelen, const char *request)
         if (av_strncasecmp(p, "Pragma:", 7) == 0) {
             const char *q = p + 7;
 
-            while (*q && *q != '\n' && isspace(*q))
+            while (*q && *q != '\n' && av_isspace(*q))
                 q++;
 
             if (av_strncasecmp(q, "stream-switch-entry=", 20) == 0) {
@@ -1135,7 +1135,7 @@ static int extract_rates(char *rates, int ratelen, const char *request)
                     if (stream_no < ratelen && stream_no >= 0)
                         rates[stream_no] = rate_no;
 
-                    while (*q && *q != '\n' && !isspace(*q))
+                    while (*q && *q != '\n' && !av_isspace(*q))
                         q++;
                 }
 
@@ -1246,7 +1246,7 @@ static void get_word(char *buf, int buf_size, const char **pp)
     p = *pp;
     skip_spaces(&p);
     q = buf;
-    while (!isspace(*p) && *p != '\0') {
+    while (!av_isspace(*p) && *p != '\0') {
         if ((q - buf) < buf_size - 1)
             *q++ = *p;
         p++;
@@ -1263,7 +1263,7 @@ static void get_arg(char *buf, int buf_size, const char **pp)
     int quote;
 
     p = *pp;
-    while (isspace(*p)) p++;
+    while (av_isspace(*p)) p++;
     q = buf;
     quote = 0;
     if (*p == '\"' || *p == '\'')
@@ -1273,7 +1273,7 @@ static void get_arg(char *buf, int buf_size, const char **pp)
             if (*p == quote)
                 break;
         } else {
-            if (isspace(*p))
+            if (av_isspace(*p))
                 break;
         }
         if (*p == '\0')
@@ -1377,7 +1377,7 @@ static IPAddressACL* parse_dynamic_acl(FFStream *stream, HTTPContext *c)
             break;
         line_num++;
         p = line;
-        while (isspace(*p))
+        while (av_isspace(*p))
             p++;
         if (*p == '\0' || *p == '#')
             continue;
@@ -1528,7 +1528,7 @@ static int http_parse_request(HTTPContext *c)
     for (p = c->buffer; *p && *p != '\r' && *p != '\n'; ) {
         if (av_strncasecmp(p, "User-Agent:", 11) == 0) {
             useragent = p + 11;
-            if (*useragent && *useragent != '\n' && isspace(*useragent))
+            if (*useragent && *useragent != '\n' && av_isspace(*useragent))
                 useragent++;
             break;
         }
@@ -1654,7 +1654,7 @@ static int http_parse_request(HTTPContext *c)
             char *eoh;
             char hostbuf[260];
 
-            while (isspace(*hostinfo))
+            while (av_isspace(*hostinfo))
                 hostinfo++;
 
             eoh = strchr(hostinfo, '\n');
@@ -4060,7 +4060,7 @@ static int parse_ffconfig(const char *filename)
             break;
         line_num++;
         p = line;
-        while (isspace(*p))
+        while (av_isspace(*p))
             p++;
         if (*p == '\0' || *p == '#')
             continue;
@@ -4198,7 +4198,7 @@ static int parse_ffconfig(const char *filename)
                 get_arg(arg, sizeof(arg), &p);
                 p1 = arg;
                 fsize = strtod(p1, &p1);
-                switch(toupper(*p1)) {
+                switch(av_toupper(*p1)) {
                 case 'K':
                     fsize *= 1024;
                     break;
diff --git a/cmdutils.c b/cmdutils.c
index fa5632672a..3dbb722d21 100644
--- a/cmdutils.c
+++ b/cmdutils.c
@@ -1289,7 +1289,7 @@ int show_help(void *optctx, const char *opt, const char *arg)
 int read_yesno(void)
 {
     int c = getchar();
-    int yesno = (toupper(c) == 'Y');
+    int yesno = (av_toupper(c) == 'Y');
 
     while (c != '\n' && c != EOF)
         c = getchar();
diff --git a/compat/strtod.c b/compat/strtod.c
index 7e979e8be6..258909f409 100644
--- a/compat/strtod.c
+++ b/compat/strtod.c
@@ -19,7 +19,6 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include <ctype.h>
 #include <limits.h>
 #include <stdlib.h>
 
@@ -49,7 +48,7 @@ double avpriv_strtod(const char *nptr, char **endptr)
     double res;
 
     /* Skip leading spaces */
-    while (isspace(*nptr))
+    while (av_isspace(*nptr))
         nptr++;
 
     if (!av_strncasecmp(nptr, "infinity", 8)) {
diff --git a/libavcodec/dvdsubdec.c b/libavcodec/dvdsubdec.c
index 7afdd27b18..ae16f05e4c 100644
--- a/libavcodec/dvdsubdec.c
+++ b/libavcodec/dvdsubdec.c
@@ -23,6 +23,7 @@
 #include "dsputil.h"
 #include "libavutil/colorspace.h"
 #include "libavutil/imgutils.h"
+#include "libavutil/avstring.h"
 
 //#define DEBUG
 
@@ -522,7 +523,7 @@ static int dvdsub_init(AVCodecContext *avctx)
             ctx->has_palette = 1;
             for (i = 0; i < 16; i++) {
                 ctx->palette[i] = strtoul(p, &p, 16);
-                while (*p == ',' || isspace(*p))
+                while (*p == ',' || av_isspace(*p))
                     p++;
             }
         } else if (!strncmp("size:", cur, 5)) {
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index b2fdd32458..2a78f7fc0e 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -2105,10 +2105,10 @@ int avpriv_unlock_avformat(void)
 
 unsigned int avpriv_toupper4(unsigned int x)
 {
-    return toupper(x & 0xFF)
-           + (toupper((x >> 8) & 0xFF) << 8)
-           + (toupper((x >> 16) & 0xFF) << 16)
-           + (toupper((x >> 24) & 0xFF) << 24);
+    return av_toupper(x & 0xFF) +
+          (av_toupper((x >>  8) & 0xFF) << 8)  +
+          (av_toupper((x >> 16) & 0xFF) << 16) +
+          (av_toupper((x >> 24) & 0xFF) << 24);
 }
 
 #if !HAVE_THREADS
diff --git a/libavfilter/af_channelmap.c b/libavfilter/af_channelmap.c
index 8b72d5bc9f..f741881f41 100644
--- a/libavfilter/af_channelmap.c
+++ b/libavfilter/af_channelmap.c
@@ -150,17 +150,17 @@ static av_cold int channelmap_init(AVFilterContext *ctx, const char *args)
     } else {
         char *dash = strchr(mapping, '-');
         if (!dash) {  // short mapping
-            if (isdigit(*mapping))
+            if (av_isdigit(*mapping))
                 mode = MAP_ONE_INT;
             else
                 mode = MAP_ONE_STR;
-        } else if (isdigit(*mapping)) {
-            if (isdigit(*(dash+1)))
+        } else if (av_isdigit(*mapping)) {
+            if (av_isdigit(*(dash+1)))
                 mode = MAP_PAIR_INT_INT;
             else
                 mode = MAP_PAIR_INT_STR;
         } else {
-            if (isdigit(*(dash+1)))
+            if (av_isdigit(*(dash+1)))
                 mode = MAP_PAIR_STR_INT;
             else
                 mode = MAP_PAIR_STR_STR;
diff --git a/libavfilter/avfiltergraph.c b/libavfilter/avfiltergraph.c
index 97af5d0323..09b32f3f42 100644
--- a/libavfilter/avfiltergraph.c
+++ b/libavfilter/avfiltergraph.c
@@ -20,7 +20,6 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include <ctype.h>
 #include <string.h>
 
 #include "libavutil/avassert.h"
diff --git a/libavfilter/graphparser.c b/libavfilter/graphparser.c
index 04339c8138..d48828ea24 100644
--- a/libavfilter/graphparser.c
+++ b/libavfilter/graphparser.c
@@ -20,7 +20,6 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include <ctype.h>
 #include <string.h>
 #include <stdio.h>
 
diff --git a/libavfilter/vf_libopencv.c b/libavfilter/vf_libopencv.c
index e558a4a9c1..25b1c5030b 100644
--- a/libavfilter/vf_libopencv.c
+++ b/libavfilter/vf_libopencv.c
@@ -177,7 +177,7 @@ static int read_shape_from_file(int *cols, int *rows, int **values, const char *
                 p++;
                 break;
             } else
-                (*values)[*cols*i + j] = !!isgraph(*(p++));
+                (*values)[*cols*i + j] = !!av_isgraph(*(p++));
         }
     }
     av_file_unmap(buf, size);
diff --git a/libavformat/hls.c b/libavformat/hls.c
index 4c0e0c0b63..0d691ec47e 100644
--- a/libavformat/hls.c
+++ b/libavformat/hls.c
@@ -108,7 +108,7 @@ typedef struct HLSContext {
 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
 {
     int len = ff_get_line(s, buf, maxlen);
-    while (len > 0 && isspace(buf[len - 1]))
+    while (len > 0 && av_isspace(buf[len - 1]))
         buf[--len] = '\0';
     return len;
 }
diff --git a/libavformat/hlsproto.c b/libavformat/hlsproto.c
index b750501c4d..fde7191c35 100644
--- a/libavformat/hlsproto.c
+++ b/libavformat/hlsproto.c
@@ -71,7 +71,7 @@ typedef struct HLSContext {
 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
 {
     int len = ff_get_line(s, buf, maxlen);
-    while (len > 0 && isspace(buf[len - 1]))
+    while (len > 0 && av_isspace(buf[len - 1]))
         buf[--len] = '\0';
     return len;
 }
diff --git a/libavformat/http.c b/libavformat/http.c
index 9645bd1ffb..730a5b1b2f 100644
--- a/libavformat/http.c
+++ b/libavformat/http.c
@@ -278,9 +278,9 @@ static int process_line(URLContext *h, char *line, int line_count,
 
     p = line;
     if (line_count == 0) {
-        while (!isspace(*p) && *p != '\0')
+        while (!av_isspace(*p) && *p != '\0')
             p++;
-        while (isspace(*p))
+        while (av_isspace(*p))
             p++;
         s->http_code = strtol(p, &end, 10);
 
@@ -305,7 +305,7 @@ static int process_line(URLContext *h, char *line, int line_count,
         *p = '\0';
         tag = line;
         p++;
-        while (isspace(*p))
+        while (av_isspace(*p))
             p++;
         if (!av_strcasecmp(tag, "Location")) {
             av_strlcpy(s->location, p, sizeof(s->location));
diff --git a/libavformat/httpauth.c b/libavformat/httpauth.c
index 774ee2134f..b96da3ef12 100644
--- a/libavformat/httpauth.c
+++ b/libavformat/httpauth.c
@@ -27,7 +27,6 @@
 #include "libavutil/md5.h"
 #include "urldecode.h"
 #include "avformat.h"
-#include <ctype.h>
 
 static void handle_basic_params(HTTPAuthState *state, const char *key,
                                 int key_len, char **dest, int *dest_len)
@@ -80,8 +79,8 @@ static void choose_qop(char *qop, int size)
     char *ptr = strstr(qop, "auth");
     char *end = ptr + strlen("auth");
 
-    if (ptr && (!*end || isspace(*end) || *end == ',') &&
-        (ptr == qop || isspace(ptr[-1]) || ptr[-1] == ',')) {
+    if (ptr && (!*end || av_isspace(*end) || *end == ',') &&
+        (ptr == qop || av_isspace(ptr[-1]) || ptr[-1] == ',')) {
         av_strlcpy(qop, "auth", size);
     } else {
         qop[0] = 0;
diff --git a/libavformat/oggparsevorbis.c b/libavformat/oggparsevorbis.c
index bb41b52ca2..db462fc865 100644
--- a/libavformat/oggparsevorbis.c
+++ b/libavformat/oggparsevorbis.c
@@ -122,7 +122,7 @@ ff_vorbis_comment(AVFormatContext * as, AVDictionary **m, const uint8_t *buf, in
             }
 
             for (j = 0; j < tl; j++)
-                tt[j] = toupper(t[j]);
+                tt[j] = av_toupper(t[j]);
             tt[tl] = 0;
 
             memcpy(ct, v, vl);
diff --git a/libavformat/rtmphttp.c b/libavformat/rtmphttp.c
index 80a983bd11..e67abba57c 100644
--- a/libavformat/rtmphttp.c
+++ b/libavformat/rtmphttp.c
@@ -236,7 +236,7 @@ static int rtmp_http_open(URLContext *h, const char *uri, int flags)
             goto fail;
         }
     }
-    while (off > 0 && isspace(rt->client_id[off - 1]))
+    while (off > 0 && av_isspace(rt->client_id[off - 1]))
         off--;
     rt->client_id[off] = '\0';
 
diff --git a/libavformat/urldecode.c b/libavformat/urldecode.c
index 32460da4f9..49af9ba1e0 100644
--- a/libavformat/urldecode.c
+++ b/libavformat/urldecode.c
@@ -26,7 +26,6 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include <ctype.h>
 #include <string.h>
 
 #include "libavutil/mem.h"
@@ -54,7 +53,7 @@ char *ff_urldecode(const char *url)
         if (c == '%' && s + 2 < url_len) {
             char c2 = url[s++];
             char c3 = url[s++];
-            if (isxdigit(c2) && isxdigit(c3)) {
+            if (av_isxdigit(c2) && av_isxdigit(c3)) {
                 c2 = av_tolower(c2);
                 c3 = av_tolower(c3);
 
diff --git a/libavformat/utils.c b/libavformat/utils.c
index be5a5caabf..a89e956d8d 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -3050,11 +3050,11 @@ int av_get_frame_filename(char *buf, int buf_size,
         if (c == '%') {
             do {
                 nd = 0;
-                while (isdigit(*p)) {
+                while (av_isdigit(*p)) {
                     nd = nd * 10 + *p++ - '0';
                 }
                 c = *p++;
-            } while (isdigit(c));
+            } while (av_isdigit(c));
 
             switch(c) {
             case '%':
@@ -3255,7 +3255,7 @@ int ff_hex_to_data(uint8_t *data, const char *p)
         p += strspn(p, SPACE_CHARS);
         if (*p == '\0')
             break;
-        c = toupper((unsigned char) *p++);
+        c = av_toupper((unsigned char) *p++);
         if (c >= '0' && c <= '9')
             c = c - '0';
         else if (c >= 'A' && c <= 'F')
@@ -3365,7 +3365,7 @@ void ff_parse_key_value(const char *str, ff_parse_key_val_cb callback_get_buf,
         int key_len, dest_len = 0;
 
         /* Skip whitespace and potential commas. */
-        while (*ptr && (isspace(*ptr) || *ptr == ','))
+        while (*ptr && (av_isspace(*ptr) || *ptr == ','))
             ptr++;
         if (!*ptr)
             break;
@@ -3398,7 +3398,7 @@ void ff_parse_key_value(const char *str, ff_parse_key_val_cb callback_get_buf,
             if (*ptr == '\"')
                 ptr++;
         } else {
-            for (; *ptr && !(isspace(*ptr) || *ptr == ','); ptr++)
+            for (; *ptr && !(av_isspace(*ptr) || *ptr == ','); ptr++)
                 if (dest && dest < dest_end)
                     *dest++ = *ptr;
         }
diff --git a/libavutil/avstring.c b/libavutil/avstring.c
index 6ce0310c1a..973ba4357e 100644
--- a/libavutil/avstring.c
+++ b/libavutil/avstring.c
@@ -23,7 +23,6 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
-#include <ctype.h>
 
 #include "config.h"
 #include "common.h"
@@ -43,7 +42,7 @@ int av_strstart(const char *str, const char *pfx, const char **ptr)
 
 int av_stristart(const char *str, const char *pfx, const char **ptr)
 {
-    while (*pfx && toupper((unsigned)*pfx) == toupper((unsigned)*str)) {
+    while (*pfx && av_toupper((unsigned)*pfx) == av_toupper((unsigned)*str)) {
         pfx++;
         str++;
     }
diff --git a/libavutil/common.h b/libavutil/common.h
index cc4df16e4a..caa6b1963b 100644
--- a/libavutil/common.h
+++ b/libavutil/common.h
@@ -26,7 +26,6 @@
 #ifndef AVUTIL_COMMON_H
 #define AVUTIL_COMMON_H
 
-#include <ctype.h>
 #include <errno.h>
 #include <inttypes.h>
 #include <limits.h>
diff --git a/libavutil/dict.c b/libavutil/dict.c
index 6532a56561..9ac4831688 100644
--- a/libavutil/dict.c
+++ b/libavutil/dict.c
@@ -18,7 +18,6 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#include <ctype.h>
 #include <string.h>
 
 #include "avstring.h"
@@ -50,7 +49,7 @@ av_dict_get(AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int
     for(; i<m->count; i++){
         const char *s= m->elems[i].key;
         if(flags & AV_DICT_MATCH_CASE) for(j=0;         s[j]  ==         key[j]  && key[j]; j++);
-        else                               for(j=0; toupper(s[j]) == toupper(key[j]) && key[j]; j++);
+        else                               for(j=0; av_toupper(s[j]) == av_toupper(key[j]) && key[j]; j++);
         if(key[j])
             continue;
         if(s[j] && !(flags & AV_DICT_IGNORE_SUFFIX))
diff --git a/libavutil/eval.c b/libavutil/eval.c
index a0e968dc34..0ca7472ffd 100644
--- a/libavutil/eval.c
+++ b/libavutil/eval.c
@@ -31,6 +31,7 @@
 #include "eval.h"
 #include "log.h"
 #include "mathematics.h"
+#include "avstring.h"
 
 typedef struct Parser {
     const AVClass *class;
@@ -503,7 +504,7 @@ int av_expr_parse(AVExpr **expr, const char *s,
         return AVERROR(ENOMEM);
 
     while (*s)
-        if (!isspace(*s++)) *wp++ = s[-1];
+        if (!av_isspace(*s++)) *wp++ = s[-1];
     *wp++ = 0;
 
     p.class      = &class;
diff --git a/libavutil/parseutils.c b/libavutil/parseutils.c
index 917451eee7..0e3fd9eab5 100644
--- a/libavutil/parseutils.c
+++ b/libavutil/parseutils.c
@@ -385,7 +385,7 @@ static int date_get_num(const char **pp,
     val = 0;
     for(i = 0; i < len_max; i++) {
         c = *p;
-        if (!isdigit(c))
+        if (!av_isdigit(c))
             break;
         val = (val * 10) + c - '0';
         p++;
@@ -591,7 +591,7 @@ int av_parse_time(int64_t *timeval, const char *timestr, int duration)
         int val, n;
         q++;
         for (val = 0, n = 100000; n >= 1; n /= 10, q++) {
-            if (!isdigit(*q))
+            if (!av_isdigit(*q))
                 break;
             val += n * (*q - '0');
         }