diff --git a/src/bootstrap_gui.cpp b/src/bootstrap_gui.cpp
index ae04d45b7b..1cfd582c0d 100644
--- a/src/bootstrap_gui.cpp
+++ b/src/bootstrap_gui.cpp
@@ -380,7 +380,7 @@ bool HandleBootstrap()
 	/* Initialise the font cache. */
 	InitializeUnicodeGlyphMap();
 	/* Next "force" finding a suitable non-sprite font as the local font is missing. */
-	CheckForMissingGlyphs(false);
+	CheckForMissingGlyphs();
 
 	/* Initialise the palette. The biggest step is 'faking' some recolour sprites.
 	 * This way the mauve and gray colours work and we can show the user interface. */
diff --git a/src/fontcache/spritefontcache.cpp b/src/fontcache/spritefontcache.cpp
index 0ed1cff34e..8d67237266 100644
--- a/src/fontcache/spritefontcache.cpp
+++ b/src/fontcache/spritefontcache.cpp
@@ -94,6 +94,7 @@ void InitializeUnicodeGlyphMap(FontSize fs)
 			SetUnicodeGlyph(fs, unicode_map.code, 0);
 		} else {
 			SpriteID sprite = base + key - ASCII_LETTERSTART;
+			if (!SpriteExists(sprite)) continue;
 			SetUnicodeGlyph(fs, unicode_map.code, sprite);
 		}
 	}
diff --git a/src/strings.cpp b/src/strings.cpp
index f4ff461bc7..b4050dca0c 100644
--- a/src/strings.cpp
+++ b/src/strings.cpp
@@ -2356,15 +2356,14 @@ class LanguagePackGlyphSearcher : public MissingGlyphSearcher {
  * mean it might use characters that are not in the
  * font, which is the whole reason this check has
  * been added.
- * @param base_font Whether to look at the base font as well.
  * @param searcher  The methods to use to search for strings to check.
  *                  If nullptr the loaded language pack searcher is used.
  */
-void CheckForMissingGlyphs(bool base_font, MissingGlyphSearcher *searcher)
+void CheckForMissingGlyphs(MissingGlyphSearcher *searcher)
 {
 	static LanguagePackGlyphSearcher pack_searcher;
 	if (searcher == nullptr) searcher = &pack_searcher;
-	bool bad_font = !base_font || searcher->FindMissingGlyphs();
+	bool bad_font = searcher->FindMissingGlyphs();
 #if defined(WITH_FREETYPE) || defined(_WIN32) || defined(WITH_COCOA)
 	if (bad_font) {
 		/* We found an unprintable character... lets try whether we can find
@@ -2390,7 +2389,7 @@ void CheckForMissingGlyphs(bool base_font, MissingGlyphSearcher *searcher)
 			ShowErrorMessage(GetEncodedString(STR_JUST_RAW_STRING, std::move(err_str)), {}, WL_WARNING);
 		}
 
-		if (bad_font && base_font) {
+		if (bad_font) {
 			/* Our fallback font does miss characters too, so keep the
 			 * user chosen font as that is more likely to be any good than
 			 * the wild guess we made */
diff --git a/src/strings_func.h b/src/strings_func.h
index 7bb9ae99ff..e883504b41 100644
--- a/src/strings_func.h
+++ b/src/strings_func.h
@@ -195,6 +195,6 @@ public:
 	bool FindMissingGlyphs();
 };
 
-void CheckForMissingGlyphs(bool base_font = true, MissingGlyphSearcher *search = nullptr);
+void CheckForMissingGlyphs(MissingGlyphSearcher *search = nullptr);
 
 #endif /* STRINGS_FUNC_H */
diff --git a/src/textfile_gui.cpp b/src/textfile_gui.cpp
index 75650c52ef..4c3f31d49b 100644
--- a/src/textfile_gui.cpp
+++ b/src/textfile_gui.cpp
@@ -923,7 +923,7 @@ void TextfileWindow::LoadText(std::string_view buf)
 	this->AfterLoadText();
 	this->ReflowContent();
 
-	CheckForMissingGlyphs(true, this);
+	CheckForMissingGlyphs(this);
 
 	/* The font may have changed when searching for glyphs, so ensure widget sizes are updated just in case. */
 	this->ReInit();