--- a/extras/gudev/docs/Makefile.in
+++ b/extras/gudev/docs/Makefile.in
@@ -300,6 +300,7 @@ GPATH = $(srcdir)
 TARGET_DIR = $(HTML_DIR)/$(DOC_MODULE)
 
 # This includes the standard gtk-doc make rules, copied by gtkdocize.
+srcdir := $(builddir)
 
 # Other files to distribute
 # e.g. EXTRA_DIST += version.xml.in
--- a/libudev/docs/Makefile.in
+++ b/libudev/docs/Makefile.in
@@ -292,6 +292,7 @@ GPATH = $(srcdir)
 TARGET_DIR = $(HTML_DIR)/$(DOC_MODULE)
 
 # This includes the standard gtk-doc make rules, copied by gtkdocize.
+srcdir := $(builddir)
 
 # Other files to distribute
 # e.g. EXTRA_DIST += version.xml.in