diff --git a/src/subtitles/RTS.cpp b/src/subtitles/RTS.cpp
index 2aa15f3f..b2213974 100644
--- a/src/subtitles/RTS.cpp
+++ b/src/subtitles/RTS.cpp
@@ -2414,6 +2414,7 @@ bool CRenderedTextSubtitle::ParseSSATag( CSubtitle* sub, const AssTagList& assTa
         case CMD_fe:
             {
                 int n = wcstol(p, NULL, 10);
+                if (n < 0) n = DEFAULT_CHARSET;
                 style.charSet = !p.IsEmpty()
                                 ? n
                                 : org.charSet;
diff --git a/src/subtitles/STS.cpp b/src/subtitles/STS.cpp
index b1d7db67..01dc8582 100644
--- a/src/subtitles/STS.cpp
+++ b/src/subtitles/STS.cpp
@@ -1502,6 +1502,7 @@ static bool OpenSubStationAlpha(CTextFile* file, CSimpleTextSubtitle& ret, int C
             {
                 CString StyleName;
                 int alpha;
+                int encoding;
                 CRect tmp_rect;
 
                 StyleName = GetStr(buff);
@@ -1526,9 +1527,11 @@ if(sver >= 4)   style->borderStyle = GetInt(buff);
 if(sver >= 6)   tmp_rect.bottom = GetInt(buff);
                 style->marginRect = tmp_rect;
 if(sver <= 4)   alpha = GetInt(buff);
-                style->charSet = GetInt(buff);
+                encoding = GetInt(buff);
 if(sver >= 6)   style->relativeTo = GetInt(buff);
 
+                // Map unsupported extension to the most permissive charSet
+                style->charSet = encoding < 0 ? DEFAULT_CHARSET : encoding;
 if(sver <= 4)   style->colors[2] = style->colors[3]; // style->colors[2] is used for drawing the outline
 if(sver <= 4)   alpha = max(min(alpha, 0xff), 0);
 if(sver <= 4)   {for(size_t i = 0; i < 3; i++) style->alpha[i] = alpha; style->alpha[3] = 0x80;}