diff --git a/CHANGES b/CHANGES
index 960919e..53fab22 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3,7 +3,9 @@ Released 2.5.0 2017-11-xx
 
 Changes since 2.4.45:
 
-This release requires pyasn1 0.3.x or newer!
+This release now strictly requires
+pyasn1 0.3.7+ and pyasn1_modules 0.1.5+
+as installation prerequisites.
 
 Lib/
 * slapdtest.SlapdObject.restart() just restarts slapd
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..465a037
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,3 @@
+pyasn1>=0.3.7
+pyasn1_modules>=0.1.5
+