diff --git a/icu4c/data/index.txt b/icu4c/data/index.txt
index f0c12a519e3..0dffdaf7c54 100644
--- a/icu4c/data/index.txt
+++ b/icu4c/data/index.txt
@@ -66,6 +66,7 @@ index {
         en_US,
         en_ZA,
         en_ZW,
+        en_US_POSIX,
         el,
         el_GR,
         el_GR_EURO,
diff --git a/icu4c/source/data/locales/index.txt b/icu4c/source/data/locales/index.txt
index f0c12a519e3..0dffdaf7c54 100644
--- a/icu4c/source/data/locales/index.txt
+++ b/icu4c/source/data/locales/index.txt
@@ -66,6 +66,7 @@ index {
         en_US,
         en_ZA,
         en_ZW,
+        en_US_POSIX,
         el,
         el_GR,
         el_GR_EURO,