diff --git a/src/strings.cpp b/src/strings.cpp
index 8a23b93daa..e069370e94 100644
--- a/src/strings.cpp
+++ b/src/strings.cpp
@@ -2158,23 +2158,20 @@ const char *GetCurrentLanguageIsoCode()
 bool MissingGlyphSearcher::FindMissingGlyphs()
 {
 	InitFontCache(this->Monospace());
-	const Sprite *question_mark[FS_END];
-
-	for (FontSize size = this->Monospace() ? FS_MONO : FS_BEGIN; size < (this->Monospace() ? FS_END : FS_MONO); size++) {
-		question_mark[size] = GetGlyph(size, '?');
-	}
 
 	this->Reset();
 	for (auto text = this->NextString(); text.has_value(); text = this->NextString()) {
 		auto src = text->cbegin();
 
 		FontSize size = this->DefaultSize();
+		FontCache *fc = FontCache::Get(size);
 		while (src != text->cend()) {
 			char32_t c = Utf8Consume(src);
 
 			if (c >= SCC_FIRST_FONT && c <= SCC_LAST_FONT) {
 				size = (FontSize)(c - SCC_FIRST_FONT);
-			} else if (!IsInsideMM(c, SCC_SPRITE_START, SCC_SPRITE_END) && IsPrintable(c) && !IsTextDirectionChar(c) && c != '?' && GetGlyph(size, c) == question_mark[size]) {
+				fc = FontCache::Get(size);
+			} else if (!IsInsideMM(c, SCC_SPRITE_START, SCC_SPRITE_END) && IsPrintable(c) && !IsTextDirectionChar(c) && fc->MapCharToGlyph(c, false) == 0) {
 				/* The character is printable, but not in the normal font. This is the case we were testing for. */
 				std::string size_name;