diff --git a/make-includes/standard_environment.make b/make-includes/standard_environment.make
index 84581a4..f786ecb 100644
--- a/make-includes/standard_environment.make
+++ b/make-includes/standard_environment.make
@@ -34,7 +34,7 @@
 ifdef LATEX_OPTS
 LATEX_OPTS+=,
 endif
-LATEX_OPTS=$(FONT_SIZE),$(PAPER_SIZE),$(DRAFT)
+LATEX_OPTS+=$(FONT_SIZE),$(PAPER_SIZE),$(DRAFT)
 #
 # List of standard "phony" build targets.
 #