Index: src/fontcache.cpp
===================================================================
--- src/fontcache.cpp	(revision 25034)
+++ src/fontcache.cpp	(working copy)
@@ -524,6 +524,15 @@
 		while (!result && ATSFontIteratorNext(itr, &font) == noErr) {
 			/* Get CoreText font handle. */
 			CTFontRef font_ref = CTFontCreateWithPlatformFont(font, 0.0, NULL, NULL);
+
+			if (callback->Monospace()) {
+				CTFontSymbolicTraits traits = CTFontGetSymbolicTraits(font_ref);
+				if ((traits & kCTFontMonoSpaceTrait) == 0) {
+					CFRelease(font_ref);
+					continue;
+				}
+			}
+
 			CFArrayRef langs = CTFontCopySupportedLanguages(font_ref);
 			if (langs != NULL) {
 				/* Font has a list of supported languages. */