diff --git a/po/Rules-lyx b/po/Rules-lyx
index 8aefa41eb2..22fdb26491 100644
--- a/po/Rules-lyx
+++ b/po/Rules-lyx
@@ -7,11 +7,12 @@ POTFILE_IN_DEPS = $(shell find $(top_srcdir)/src -name Makefile.am)
 
 $(DOMAIN).pot-update: l10n_pots
 
+# The ui_*.h and moc_*.cpp filters must match the patterns in src/frontends/qt4/Makefile.am
 ${srcdir}/POTFILES.in: $(POTFILE_IN_DEPS)
 	LC_ALL=C ; export LC_ALL ; \
 	rm -f $@-t \
 	&& ( cd $(top_srcdir); \
-	     grep -l "_(\".*\")" `find src \( -name '*.h' -o -name '*.cpp' -o -name '*.cpp.in' \) -print` |\
+	     grep -l "_(\".*\")" `find src \( \( -name '*.h' -a ! -name 'ui_*.h' \) -o \( -name '*.cpp' -a ! -name 'moc_*.cpp' \) \) -print` |\
 	     grep -v -e "src/support/Package.cpp$$" |\
 	     sort | uniq ) > $@-t \
 	&& mv $@-t $@
diff --git a/src/frontends/qt4/Makefile.am b/src/frontends/qt4/Makefile.am
index caa41159ae..299e3ca9e7 100644
--- a/src/frontends/qt4/Makefile.am
+++ b/src/frontends/qt4/Makefile.am
@@ -10,11 +10,13 @@ CLEANFILES += $(BUILT_SOURCES)
 # Use _() for localization instead of tr() or trUtf8()
 UIC4FLAGS=-tr lyx::qt_
 
+# The ui_%.h pattern must match the filter in ../../../po/Rules-lyx
 ui_%.h: ui/%.ui
 	$(AM_V_GEN)$(UIC4) $(UIC4FLAGS) $< -o $@
 
 MOCEDFILES = $(MOCHEADER:%.h=moc_%.cpp)
 
+# The moc_%.cpp pattern must match the filter in ../../../po/Rules-lyx
 moc_%.cpp: %.h
 	$(AM_V_GEN)$(MOC4) -o $@ $<