diff --git a/pkgs/development/libraries/icu/default.nix b/pkgs/development/libraries/icu/default.nix
index a7c528336a9b..ec5447a751b4 100644
--- a/pkgs/development/libraries/icu/default.nix
+++ b/pkgs/development/libraries/icu/default.nix
@@ -23,6 +23,10 @@ let
   };
 in
 {
+  icu78 = make-icu {
+    version = "78.1";
+    hash = "sha256-Yhf1jKObIxJ2Bc/Gx+DTR1/ksNYxVwETg9cWy0FheIY=";
+  };
   icu77 = make-icu {
     version = "77.1";
     hash = "sha256-WI5DH3cyfDkDH/u4hDwOO8EiwhE3RIX6h9xfP6/yQGE=";
diff --git a/pkgs/development/libraries/icu/make-icu.nix b/pkgs/development/libraries/icu/make-icu.nix
index 0ba9681e26df..e12208aedb39 100644
--- a/pkgs/development/libraries/icu/make-icu.nix
+++ b/pkgs/development/libraries/icu/make-icu.nix
@@ -30,9 +30,13 @@ let
 
   baseAttrs = {
     src = fetchurl {
-      url = "https://github.com/unicode-org/icu/releases/download/release-${release}/icu4c-${
-        lib.replaceStrings [ "." ] [ "_" ] version
-      }-src.tgz";
+      url =
+        if lib.versionAtLeast version "78.1" then
+          "https://github.com/unicode-org/icu/releases/download/release-${version}/icu4c-${version}-sources.tgz"
+        else
+          "https://github.com/unicode-org/icu/releases/download/release-${release}/icu4c-${
+            lib.replaceStrings [ "." ] [ "_" ] version
+          }-src.tgz";
       inherit hash;
     };
 
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 0ff2404eb4ca..b5e05b0616dc 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -7474,6 +7474,7 @@ with pkgs;
     icu75
     icu76
     icu77
+    icu78
     ;
 
   icu = icu76;