diff --git a/tests/Makefile.am b/tests/Makefile.am
index 641b35c..1be6308 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -12,7 +12,9 @@ OSMO_GSM_MANUALS_NO_INSTALL = 1
 # Generate adoc file that includes all chapters (OS#4183: glossary.adoc must be the last file)
 ASCIIDOC = test-usermanual.adoc
 ASCIIDOC_DEPS =
-COMMON_CHAPTERS = $(shell find $(OSMO_GSM_MANUALS_DIR)/common/chapters -name '*.adoc' | grep -v glossary\.adoc) \
+COMMON_CHAPTERS = $(shell find $(OSMO_GSM_MANUALS_DIR)/common/chapters -name '*.adoc' \
+			! -name glossary.adoc \
+			! -name mgcp_extension_osmux.adoc) \
 		  $(OSMO_GSM_MANUALS_DIR)/common/chapters/glossary.adoc
 $(ASCIIDOC): $(COMMON_CHAPTERS)
 	echo ":gfdl-enabled:" > $@