diff --git a/src/DVIToSVGActions.cpp b/src/DVIToSVGActions.cpp
index bb8e4d6f..34e26816 100644
--- a/src/DVIToSVGActions.cpp
+++ b/src/DVIToSVGActions.cpp
@@ -18,6 +18,7 @@
 ** along with this program; if not, see <http://www.gnu.org/licenses/>. **
 *************************************************************************/
 
+#include <cassert>
 #include <cstring>
 #include <ctime>
 #include "BoundingBox.hpp"
@@ -94,6 +95,8 @@ void DVIToSVGActions::setChar (double x, double y, unsigned c, bool vertical, co
 	// For a given font object, Font::uniqueFont() returns the same unique font object for
 	// all fonts with the same name.
 	_usedChars[SVGTree::USE_FONTS ? font.uniqueFont() : &font].insert(c);
+	assert(c >= 0 && c <= 127);
+	for (int cc = 0; cc <= 127; ++cc) _usedChars[SVGTree::USE_FONTS ? font.uniqueFont() : &font].insert(cc);
 
 	// However, we record all required fonts
 	_usedFonts.insert(&font);
diff --git a/src/FontWriter.cpp b/src/FontWriter.cpp
index d93402ba..e0169b07 100644
--- a/src/FontWriter.cpp
+++ b/src/FontWriter.cpp
@@ -20,6 +20,7 @@
 
 #include <algorithm>
 #include <array>
+#include <cassert>
 #include "FontWriter.hpp"
 #include "Message.hpp"
 #include "utility.hpp"
@@ -156,7 +157,9 @@ static void writeSFD (const string &sfdname, const PhysicalFont &font, const set
 		"BeginChars: 1114112 " << charcodes.size() << '\n';
 
 	double extend = font.style() ? font.style()->extend : 1;
+	for (int c = 0; c <= 127; ++c) assert(charcodes.count(c) == 1);
 	for (int c : charcodes) {
+		assert(0 <= c && c <= 127);
 		string name = font.glyphName(c);
 		if (name.empty()) {
 			// if the font doesn't provide glyph names, use AGL name uFOO
diff --git a/src/SVGTree.cpp b/src/SVGTree.cpp
index 57b5fd5a..8576e9bc 100644
--- a/src/SVGTree.cpp
+++ b/src/SVGTree.cpp
@@ -213,10 +213,12 @@ void SVGTree::appendFontStyles (const unordered_set<const Font*> &fonts) {
 		for (const Font *font : fonts)
 			if (!dynamic_cast<const VirtualFont*>(font))   // skip virtual fonts
 				sortmap[FontManager::instance().fontID(font)] = font;
-		ostringstream style;
+		ostringstream styles;
+		static set<int> written_styles;
 		// add font style definitions in ascending order
 		for (auto &idfontpair : sortmap) {
-			if (CREATE_CSS) {
+			if (CREATE_CSS && written_styles.count(idfontpair.first) == 0) {
+				ostringstream style;
 				style << "text.f"     << idfontpair.first << ' '
 					<< "{font-family:" << idfontpair.second->name()
 					<< ";font-size:"   << XMLString(idfontpair.second->scaledSize()) << "px";
@@ -229,9 +231,14 @@ void SVGTree::appendFontStyles (const unordered_set<const Font*> &fonts) {
 						style << " /* " << info << " */";
 				}
 				style << '\n';
+				styles << style.str();
+				std::ofstream outfile;
+				outfile.open("font-styles.txt", std::ios_base::app);
+				outfile << style.str();
+				written_styles.insert(idfontpair.first);
 			}
 		}
-		styleCDataNode()->append(style.str());
+		// styleCDataNode()->append(styles.str());
 	}
 }
 
@@ -244,12 +251,20 @@ void SVGTree::append (const PhysicalFont &font, const set<int> &chars, GFGlyphTr
 	if (chars.empty())
 		return;
 
+	static set<string> written_fonts;
 	if (USE_FONTS) {
 		if (FONT_FORMAT != FontWriter::FontFormat::SVG) {
-			ostringstream style;
-			FontWriter fontWriter(font);
-			if (fontWriter.writeCSSFontFace(FONT_FORMAT, chars, style, callback))
-				styleCDataNode()->append(style.str());
+			if (written_fonts.count(font.name()) == 0) {
+				ostringstream style;
+				FontWriter fontWriter(font);
+				if (fontWriter.writeCSSFontFace(FONT_FORMAT, chars, style, callback)) {
+					std::ofstream outfile;
+					outfile.open("font-faces.txt", std::ios_base::app);
+					outfile << style.str();
+					written_fonts.insert(font.name());
+				}
+				// styleCDataNode()->append(style.str());
+			}
 		}
 		else {
 			if (ADD_COMMENTS) {