diff --git a/configure.ac b/configure.ac
index d7740b1d8..410a1fc31 100644
--- a/configure.ac
+++ b/configure.ac
@@ -819,7 +819,7 @@ AC_ARG_ENABLE(external-ortp,
 		no)	external_ortp=false ;;
 		*)	AC_MSG_ERROR(bad value ${enableval} for --enable-external-ortp) ;;
 	esac],
-	[external_ortp=false]
+	[external_ortp=$(if test -d oRTP; then printf false; else printf true; fi)]
 )
 
 if test "$external_ortp" = 'true'; then
@@ -847,7 +847,7 @@ AC_SUBST([ORTP_DIR])
 
 AC_ARG_ENABLE([external-mediastreamer],
 	[AS_HELP_STRING([--enable-external-mediastreamer],[Use external mediastreamer library])],,
-	[enable_external_mediastreamer=no]
+	[enable_external_mediastreamer=$(if test -d mediastreamer2; then printf no; else printf yes; fi)]
 )
 
 AS_CASE($enable_external_mediastreamer,
diff --git a/coreapi/Makefile.am b/coreapi/Makefile.am
index 887dd63c8..1ea19e35c 100644
--- a/coreapi/Makefile.am
+++ b/coreapi/Makefile.am
@@ -202,6 +202,8 @@ make_gitversion_h:
 			cp -f $(builddir)/$(GITVERSION_FILE_TMP) $(builddir)/$(GITVERSION_FILE) ; \
 		fi ; \
 		rm -f $(builddir)/$(GITVERSION_FILE_TMP) ; \
+	else \
+		touch $(GITVERSION_FILE) ; \
 	fi
 
 $(GITVERSION_FILE): make_gitversion_h