diff --git a/constraints/eevr.ucf b/constraints/eevr.ucf
new file mode 100644
index 0000000..acf8c9d
--- /dev/null
+++ b/constraints/eevr.ucf
@@ -0,0 +1,6 @@
+# FIFO clock crossing for streaming interface:
+# constrain to have less delay than one clock cycle of the faster clock:
+
+set_max_delay -datapath_only -from <ClkA> -to <ClkB> <faster_clock_period>
+set_max_delay -datapath_only -from <ClkB> -to <ClkA> <faster_clock_period>
+