diff --git a/modules/programs/firefox/profiles/search.nix b/modules/programs/firefox/profiles/search.nix
index 074692b48..82c346503 100644
--- a/modules/programs/firefox/profiles/search.nix
+++ b/modules/programs/firefox/profiles/search.nix
@@ -57,7 +57,10 @@ let
     in if requiredInput.isAppProvided then
       requiredInput
     else
-      processCustomEngineInput (input // requiredInput);
+      pipe (input // requiredInput) [
+        migrateEngineToV11
+        processCustomEngineInput
+      ];
 
   buildEngineConfig = name: input:
     mapAttrs' (name: value: {
@@ -91,7 +94,7 @@ let
   };
 
   settings = {
-    version = 7;
+    version = 11;
     engines = sortEngineConfigs (mapAttrs buildEngineConfig engineInput);
 
     metaData = optionalAttrs (config.default != null) {
@@ -323,6 +326,23 @@ let
       }' instead of '${engine}'" engineNameToId.${engine}
     else
       engine;
+
+  migrateEngineToV11 = engine:
+    engine // lib.optionalAttrs (engine ? iconMapObj) {
+      iconMapObj = mapAttrs' (name: value:
+        let nameToIntResult = builtins.tryEval (toInt name);
+        in {
+          name = if nameToIntResult.success then
+            name
+          else
+            let size = toString (builtins.fromJSON name).width;
+            in warn
+            "JSON object names for 'iconMapObj' are deprecated, use '${size}' instead of '${name}'"
+            size;
+
+          inherit value;
+        }) engine.iconMapObj;
+    };
 in {
   imports = [ (pkgs.path + "/nixos/modules/misc/meta.nix") ];
 
diff --git a/tests/modules/programs/firefox/profiles/search/default.nix b/tests/modules/programs/firefox/profiles/search/default.nix
index a2a9a526f..1818ccc4f 100644
--- a/tests/modules/programs/firefox/profiles/search/default.nix
+++ b/tests/modules/programs/firefox/profiles/search/default.nix
@@ -142,6 +142,27 @@ in {
         };
       };
 
+      migrateIconsV11 = {
+        id = 3;
+        search = {
+          force = true;
+          engines = {
+            nixos-wiki = {
+              name = "NixOS Wiki";
+
+              urls = [{
+                template =
+                  "https://wiki.nixos.org/w/index.php?search={searchTerms}";
+              }];
+
+              iconMapObj."{\"width\":16,\"height\":16}" =
+                "https://wiki.nixos.org/favicon.ico";
+
+              definedAliases = [ "@nw" ];
+            };
+          };
+        };
+      };
     };
   } // {
     nmt.script = let
@@ -187,6 +208,10 @@ in {
       assertFirefoxSearchContent \
         home-files/${cfg.configPath}/migrateSearchV7/search.json.mozlz4 \
         ${withName ./expected-migrate-search-v7.json}
+
+      assertFirefoxSearchContent \
+        home-files/${cfg.configPath}/migrateIconsV11/search.json.mozlz4 \
+        ${withName ./expected-migrate-icons-v11.json}
     '';
   });
 }
diff --git a/tests/modules/programs/firefox/profiles/search/expected-migrate-icons-v11.json b/tests/modules/programs/firefox/profiles/search/expected-migrate-icons-v11.json
new file mode 100644
index 000000000..c3d5c15f2
--- /dev/null
+++ b/tests/modules/programs/firefox/profiles/search/expected-migrate-icons-v11.json
@@ -0,0 +1,26 @@
+{
+  "engines": [
+    {
+      "_definedAliases": [
+        "@nw"
+      ],
+      "_iconMapObj": {
+        "16": "https://wiki.nixos.org/favicon.ico"
+      },
+      "_isAppProvided": false,
+      "_loadPath": "[home-manager]/programs.@name@.profiles.migrateIconsV11.search.engines.nixos-wiki",
+      "_metaData": {},
+      "_name": "NixOS Wiki",
+      "_urls": [
+        {
+          "template": "https://wiki.nixos.org/w/index.php?search={searchTerms}"
+        }
+      ],
+      "id": "nixos-wiki"
+    }
+  ],
+  "metaData": {
+    "useSavedOrder": false
+  },
+  "version": 11
+}
diff --git a/tests/modules/programs/firefox/profiles/search/expected-migrate-search-v7.json b/tests/modules/programs/firefox/profiles/search/expected-migrate-search-v7.json
index 850afc6e3..123eeaf6f 100644
--- a/tests/modules/programs/firefox/profiles/search/expected-migrate-search-v7.json
+++ b/tests/modules/programs/firefox/profiles/search/expected-migrate-search-v7.json
@@ -75,5 +75,5 @@
     "privateDefaultEngineIdHash": "@privateHash@",
     "useSavedOrder": true
   },
-  "version": 7
+  "version": 11
 }
diff --git a/tests/modules/programs/firefox/profiles/search/expected-search-without-default.json b/tests/modules/programs/firefox/profiles/search/expected-search-without-default.json
index 2ba4691d9..42eea4e71 100644
--- a/tests/modules/programs/firefox/profiles/search/expected-search-without-default.json
+++ b/tests/modules/programs/firefox/profiles/search/expected-search-without-default.json
@@ -38,5 +38,5 @@
   "metaData": {
     "useSavedOrder": true
   },
-  "version": 7
+  "version": 11
 }
diff --git a/tests/modules/programs/firefox/profiles/search/expected-search.json b/tests/modules/programs/firefox/profiles/search/expected-search.json
index 8688aea15..d7c0ffece 100644
--- a/tests/modules/programs/firefox/profiles/search/expected-search.json
+++ b/tests/modules/programs/firefox/profiles/search/expected-search.json
@@ -75,5 +75,5 @@
     "privateDefaultEngineIdHash": "@privateHash@",
     "useSavedOrder": true
   },
-  "version": 7
+  "version": 11
 }