diff --git a/pkgs/by-name/cj/cjson/package.nix b/pkgs/by-name/cj/cjson/package.nix
index b04408ec499b..c1fa9f4c55cd 100644
--- a/pkgs/by-name/cj/cjson/package.nix
+++ b/pkgs/by-name/cj/cjson/package.nix
@@ -22,11 +22,24 @@ stdenv.mkDerivation rec {
     lib.cmakeBool "ENABLE_CUSTOM_COMPILER_FLAGS" false
   );
 
-  # cJSON actually uses C99 standard, not C89
-  # https://github.com/DaveGamble/cJSON/issues/275
-  postPatch = ''
-    substituteInPlace CMakeLists.txt --replace -std=c89 -std=c99
-  '';
+  postPatch =
+    # cJSON actually uses C99 standard, not C89
+    # https://github.com/DaveGamble/cJSON/issues/275
+    ''
+      substituteInPlace CMakeLists.txt --replace -std=c89 -std=c99
+    ''
+    # Fix the build with CMake 4.
+    #
+    # See:
+    # * <https://github.com/DaveGamble/cJSON/issues/946>
+    # * <https://github.com/DaveGamble/cJSON/pull/935>
+    # * <https://github.com/DaveGamble/cJSON/pull/949>
+    + ''
+      substituteInPlace CMakeLists.txt \
+        --replace-fail \
+          'cmake_minimum_required(VERSION 3.0)' \
+          'cmake_minimum_required(VERSION 3.10)'
+    '';
 
   meta = with lib; {
     homepage = "https://github.com/DaveGamble/cJSON";