diff --git a/SparkleShare/Nautilus/Makefile.am b/SparkleShare/Nautilus/Makefile.am
index feb9a115..dedd2f6e 100644
--- a/SparkleShare/Nautilus/Makefile.am
+++ b/SparkleShare/Nautilus/Makefile.am
@@ -2,7 +2,7 @@ SOURCES =  \
 	sparkleshare-nautilus-extension.py
 
 if NAUTILUS_EXTENSION_ENABLED
-NAUTILUS_PYTHON_INSTALL_DIR=$(subst $(NAUTILUS_LIBDIR),${libdir},$(NAUTILUS_PYTHON_DIR))
+NAUTILUS_PYTHON_INSTALL_DIR=$(subst "$(NAUTILUS_LIBDIR)/","${libdir}/",$(NAUTILUS_PYTHON_DIR))
 extensiondir = $(NAUTILUS_PYTHON_INSTALL_DIR)
 extension_SCRIPTS = $(addprefix $(srcdir)/, $(SOURCES))
 else