diff --git a/ui/gtk3/Makefile.am b/ui/gtk3/Makefile.am
index 3ada6501..2066a8f5 100644
--- a/ui/gtk3/Makefile.am
+++ b/ui/gtk3/Makefile.am
@@ -304,6 +304,8 @@ panelbinding.o: $(srcdir)/panelbinding.c
 	$(AM_V_CC_no)$(COMPILE) -c -o $@ $<
 	$(NULL)
 
+.NOTPARALLEL:
+
 MAINTAINERCLEANFILES += extension.c panelbinding.c
 
 man_seven_DATA = ibus-emoji.7