diff --git a/java/Makefile.am b/java/Makefile.am
index d1c0da4c6..b49c3034f 100644
--- a/java/Makefile.am
+++ b/java/Makefile.am
@@ -96,4 +96,8 @@ TESTS_ENVIRONMENT = \
 t/%.class: t/%.java
 	$(JAVAC) $(JAVAC_FLAGS) -classpath libguestfs-$(VERSION).jar $<
 
-endif
\ No newline at end of file
+endif
+
+# Tell version 3.79 and up of GNU make to not build goals in this
+# directory in parallel.
+.NOTPARALLEL:
diff --git a/libguestfs.spec.in b/libguestfs.spec.in
index fa5501454..684f272c6 100644
--- a/libguestfs.spec.in
+++ b/libguestfs.spec.in
@@ -254,8 +254,7 @@ createrepo repo
 
 # 'INSTALLDIRS' ensures that perl libs are installed in the vendor dir
 # not the site dir.
-# Uses javac which is incompatible with parallel make.
-make INSTALLDIRS=vendor
+make INSTALLDIRS=vendor %{?_smp_mflags}
 
 
 %check