diff --git a/Makefile b/Makefile
index 111082ce54..a0c1430b40 100644
--- a/Makefile
+++ b/Makefile
@@ -324,8 +324,19 @@ endif
 endif
 endif
 
+# Sphinx does not allow building manuals into the same directory as
+# the source files, so if we're doing an in-tree QEMU build we must
+# build the manuals into a subdirectory (and then install them from
+# there for 'make install'). For an out-of-tree build we can just
+# use the docs/ subdirectory in the build tree as normal.
+ifeq ($(realpath $(SRC_PATH)),$(realpath .))
+MANUAL_BUILDDIR := docs/built
+else
+MANUAL_BUILDDIR := docs
+endif
+
 ifdef BUILD_DOCS
-DOCS=qemu-doc.html qemu-doc.txt qemu.1 qemu-img.1 qemu-nbd.8 docs/interop/qemu-ga.8
+DOCS=qemu-doc.html qemu-doc.txt qemu.1 qemu-img.1 qemu-nbd.8 $(MANUAL_BUILDDIR)/interop/qemu-ga.8
 DOCS+=docs/interop/qemu-qmp-ref.html docs/interop/qemu-qmp-ref.txt docs/interop/qemu-qmp-ref.7
 DOCS+=docs/interop/qemu-ga-ref.html docs/interop/qemu-ga-ref.txt docs/interop/qemu-ga-ref.7
 DOCS+=docs/qemu-block-drivers.7
@@ -699,17 +710,6 @@ dist: qemu-$(VERSION).tar.bz2
 qemu-%.tar.bz2:
 	$(SRC_PATH)/scripts/make-release "$(SRC_PATH)" "$(patsubst qemu-%.tar.bz2,%,$@)"
 
-# Sphinx does not allow building manuals into the same directory as
-# the source files, so if we're doing an in-tree QEMU build we must
-# build the manuals into a subdirectory (and then install them from
-# there for 'make install'). For an out-of-tree build we can just
-# use the docs/ subdirectory in the build tree as normal.
-ifeq ($(realpath $(SRC_PATH)),$(realpath .))
-MANUAL_BUILDDIR := docs/built
-else
-MANUAL_BUILDDIR := docs
-endif
-
 define clean-manual =
 rm -rf $(MANUAL_BUILDDIR)/$1/_static
 rm -f $(MANUAL_BUILDDIR)/$1/objects.inv $(MANUAL_BUILDDIR)/$1/searchindex.js $(MANUAL_BUILDDIR)/$1/*.html
@@ -819,7 +819,7 @@ ifdef CONFIG_TRACE_SYSTEMTAP
 	$(INSTALL_DATA) scripts/qemu-trace-stap.1 "$(DESTDIR)$(mandir)/man1"
 endif
 ifneq (,$(findstring qemu-ga,$(TOOLS)))
-	$(INSTALL_DATA) docs/interop/qemu-ga.8 "$(DESTDIR)$(mandir)/man8"
+	$(INSTALL_DATA) $(MANUAL_BUILDDIR)/interop/qemu-ga.8 "$(DESTDIR)$(mandir)/man8"
 	$(INSTALL_DATA) docs/interop/qemu-ga-ref.html "$(DESTDIR)$(qemu_docdir)"
 	$(INSTALL_DATA) docs/interop/qemu-ga-ref.txt "$(DESTDIR)$(qemu_docdir)"
 	$(INSTALL_DATA) docs/interop/qemu-ga-ref.7 "$(DESTDIR)$(mandir)/man7"