diff --git a/make-includes/build_lecture_rules.make b/make-includes/build_lecture_rules.make
index 62d6f9e..4837053 100755
--- a/make-includes/build_lecture_rules.make
+++ b/make-includes/build_lecture_rules.make
@@ -199,7 +199,7 @@
 #
 combined: $(COMBINED).pdf
 
-$(COMBINED).pdf: $(COMBINED_PREREQS)
+$(COMBINED).pdf: $(COMBINED_PREREQS) $(COMBI_IMAGES) $(COMBI_FILES)
 	pdflatex $<
 	pdflatex $<