diff --git a/include/ofxImageEffect.h b/include/ofxImageEffect.h
index 8d1c678a..1ac4b629 100644
--- a/include/ofxImageEffect.h
+++ b/include/ofxImageEffect.h
@@ -589,6 +589,19 @@ This value will be the same for all instances of a plugin.
 */
 #define kOfxImageEffectPropPluginHandle "OfxImageEffectPropPluginHandle"
 
+/** @brief Uniquely identifies a plugin instance.
+
+   - Type - ASCII string X 1
+   - Property Set - plugin instance (read only)
+
+This is host set and allows a plugin to differentiate between instances of itself just as a host's end user would.
+
+This can be useful for seeding a random number generator without requiring end user intervention.
+
+The host should make sure that this value is peristent across sessions and that the value is truly unique.
+*/
+#define kOfxImageEffectPropUniqueIdentifier "OfxImageEffectPropUniqueIdentifier"
+
 /** @brief Indicates if a host is a background render.
 
    - Type - int X 1
diff --git a/release-notes.md b/release-notes.md
index c9f59243..98d4122a 100644
--- a/release-notes.md
+++ b/release-notes.md
@@ -24,6 +24,7 @@ This is version 1.6 of the OpenFX API.
 ## Detailed List of Changes
 
 - Add `kOfxImageEffectPropNoSpatialAwareness`. Allows the host and plugin to coordinate a render that ensures no spatial changes to the image.
+- Add `kOfxImageEffectPropUniqueIdentifier`. Allows the plugin to differentiate its instances (e.g. for stably seeding a random number generator per-instance).
 
 # Release Notes - 1.5