diff --git a/libavcodec/htmlsubtitles.c b/libavcodec/htmlsubtitles.c
index fe991678d5..9575464063 100644
--- a/libavcodec/htmlsubtitles.c
+++ b/libavcodec/htmlsubtitles.c
@@ -117,12 +117,12 @@ int ff_htmlmarkup_to_ass(void *log_ctx, AVBPrint *dst, const char *in)
                 if ((param = strchr(tagname, ' ')))
                     *param++ = 0;
                 if ((!tag_close && sptr < FF_ARRAY_ELEMS(stack)) ||
-                    ( tag_close && sptr > 0 && !strcmp(stack[sptr-1].tag, tagname))) {
+                    ( tag_close && sptr > 0 && !av_strcasecmp(stack[sptr-1].tag, tagname))) {
                     int i, j, unknown = 0;
                     in += len + tag_close;
                     if (!tag_close)
                         memset(stack+sptr, 0, sizeof(*stack));
-                    if (!strcmp(tagname, "font")) {
+                    if (!av_strcasecmp(tagname, "font")) {
                         if (tag_close) {
                             for (i=PARAM_NUMBER-1; i>=0; i--)
                                 if (stack[sptr-1].param[i][0])
@@ -133,7 +133,7 @@ int ff_htmlmarkup_to_ass(void *log_ctx, AVBPrint *dst, const char *in)
                                         }
                         } else {
                             while (param) {
-                                if (!strncmp(param, "size=", 5)) {
+                                if (!av_strncasecmp(param, "size=", 5)) {
                                     unsigned font_size;
                                     param += 5 + (param[5] == '"');
                                     if (sscanf(param, "%u", &font_size) == 1) {
@@ -141,13 +141,13 @@ int ff_htmlmarkup_to_ass(void *log_ctx, AVBPrint *dst, const char *in)
                                              sizeof(stack[0].param[PARAM_SIZE]),
                                              "{\\fs%u}", font_size);
                                     }
-                                } else if (!strncmp(param, "color=", 6)) {
+                                } else if (!av_strncasecmp(param, "color=", 6)) {
                                     param += 6 + (param[6] == '"');
                                     snprintf(stack[sptr].param[PARAM_COLOR],
                                          sizeof(stack[0].param[PARAM_COLOR]),
                                          "{\\c&H%X&}",
                                          html_color_parse(log_ctx, param));
-                                } else if (!strncmp(param, "face=", 5)) {
+                                } else if (!av_strncasecmp(param, "face=", 5)) {
                                     param += 5 + (param[5] == '"');
                                     len = strcspn(param,
                                                   param[-1] == '"' ? "\"" :" ");
@@ -165,9 +165,9 @@ int ff_htmlmarkup_to_ass(void *log_ctx, AVBPrint *dst, const char *in)
                                 if (stack[sptr].param[i][0])
                                     av_bprintf(dst, "%s", stack[sptr].param[i]);
                         }
-                    } else if (tagname[0] && !tagname[1] && strspn(tagname, "bisu") == 1) {
-                        av_bprintf(dst, "{\\%c%d}", tagname[0], !tag_close);
-                    } else if (!strcmp(tagname, "br")) {
+                    } else if (tagname[0] && !tagname[1] && av_stristr("bisu", tagname)) {
+                        av_bprintf(dst, "{\\%c%d}", (char)av_tolower(tagname[0]), !tag_close);
+                    } else if (!av_strcasecmp(tagname, "br")) {
                         av_bprintf(dst, "\\N");
                     } else {
                         unknown = 1;