diff --git a/make-includes/build_misc_rules.make b/make-includes/build_misc_rules.make
index fd352e4..b06217d 100755
--- a/make-includes/build_misc_rules.make
+++ b/make-includes/build_misc_rules.make
@@ -110,7 +110,7 @@
 # PDF files exist. They will be caught by by the "clean" target though.
 #
 TIDY_FILES+=*.tmp *.out *.log *.nav *.toc *.snm *.head *.dvi *-derived.xml
-CLEAN_FILES+=*.aux $(IMGDIR)/*-print.pdf $(IMGDIR)/*-web.png
+CLEAN_FILES+=*.aux $(IMGDIR)/*-print.pdf $(IMGDIR)/*-web.png $(IMGDIR)/*-web-zoom.png
 ifdef HAS_ANSWERS
 TIDY_FILES+=$(PRINT_QUESTIONS_TEX) $(PRINT_ANSWERS_TEX)
 CLEAN_FILES+=$(WEB_QUESTIONS_HTML) $(WEB_ANSWERS_HTML) \