diff --git a/src/server/internalServer.cpp b/src/server/internalServer.cpp
index f593b6b20..378f516fd 100644
--- a/src/server/internalServer.cpp
+++ b/src/server/internalServer.cpp
@@ -211,6 +211,16 @@ void checkBookNumber(const Library::BookIdSet& bookIds, size_t limit) {
   }
 }
 
+typedef std::set<std::string> Languages;
+
+Languages getLanguages(const Library& lib, const Library::BookIdSet& bookIds) {
+  Languages langs;
+  for ( const auto& b : bookIds ) {
+    langs.insert(lib.getBookById(b).getLanguage());
+  }
+  return langs;
+}
+
 struct CustomizedResourceData
 {
   std::string mimeType;
@@ -306,6 +316,10 @@ SearchInfo InternalServer::getSearchInfo(const RequestContext& request) const
 {
   auto bookIds = selectBooks(request);
   checkBookNumber(bookIds.second, m_multizimSearchLimit);
+  if ( getLanguages(*mp_library, bookIds.second).size() != 1 ) {
+    throw Error(nonParameterizedMessage("confusion-of-tongues"));
+  }
+
   auto pattern = request.get_optional_param<std::string>("pattern", "");
   GeoQuery geoQuery;
 
diff --git a/static/i18n/en.json b/static/i18n/en.json
index 89c83c915..bf8441fc1 100644
--- a/static/i18n/en.json
+++ b/static/i18n/en.json
@@ -27,4 +27,5 @@
 	, "home-button-text": "Go to the main page of '{{BOOK_TITLE}}'"
 	, "random-page-button-text": "Go to a randomly selected page"
 	, "searchbox-tooltip": "Search '{{BOOK_TITLE}}'"
+	, "confusion-of-tongues": "Two or more books in different languages would participate in search, which may lead to confusing results."
 }
diff --git a/test/data/lib_for_server_search_test.xml b/test/data/lib_for_server_search_test.xml
new file mode 100644
index 000000000..994c6a6fa
--- /dev/null
+++ b/test/data/lib_for_server_search_test.xml
@@ -0,0 +1,4 @@
+<library version="20110515">
+  <book id="5dc0b3af-5df2-0925-f0ca-d2bf75e78af6" path="example.zim" title="Wikibooks" description="testZim" language="eng" creator="test" publisher="test" tags="_ftindex:yes;_ftindex:yes;_pictures:yes;_videos:yes;_details:yes" date="2021-04-17" mediaCount="22" size="253" />
+  <book id="6f1d19d0-633f-087b-fb55-7ac324ff9baf" path="zimfile.zim" title="Ray Charles" description="Wikipedia articles about Ray Charles" language="eng" creator="Wikipedia" publisher="Kiwix" name="wikipedia_en_ray_charles" flavour="_mini" tags="wikipedia;_category:wikipedia;_pictures:no;_videos:no;_details:no;_ftindex:yes" date="2020-03-31" articleCount="129" mediaCount="45" size="555" />
+</library>
diff --git a/test/meson.build b/test/meson.build
index b91f8cd0f..90b7ce892 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -37,6 +37,7 @@ if gtest_dep.found() and not meson.is_cross_build()
       'corner_cases.zim',
       'poor.zim',
       'library.xml',
+      'lib_for_server_search_test.xml',
       'customized_resources.txt',
       'helloworld.txt',
       'welcome.html',
diff --git a/test/server_search.cpp b/test/server_search.cpp
index 4f301f3e3..ca6bc1651 100644
--- a/test/server_search.cpp
+++ b/test/server_search.cpp
@@ -6,6 +6,17 @@
 #define SERVER_PORT 8101
 #include "server_testing_tools.h"
 
+
+class ServerSearchTest : public ServerTest
+{
+  void SetUp() override {
+    zfs1_.reset(new ZimFileServer(SERVER_PORT,
+                                  ZimFileServer::DEFAULT_OPTIONS,
+                                  "./test/lib_for_server_search_test.xml")
+    );
+  }
+};
+
 std::string makeSearchResultsHtml(const std::string& pattern,
                                   const std::string& header,
                                   const std::string& results,
@@ -555,7 +566,7 @@ const std::vector<SearchResult> LARGE_SEARCH_RESULTS = {
 //
 // In order to be able to share the same expected output data
 // LARGE_SEARCH_RESULTS between multiple build platforms and test-points
-// of the ServerTest.searchResults test-case
+// of the ServerSearchTest.searchResults test-case
 //
 // 1. Snippets are excluded from the plain-text comparison of actual and
 //    expected HTML strings. This is done with the help of the
@@ -916,7 +927,7 @@ struct TestData
   }
 };
 
-TEST_F(ServerTest, searchResults)
+TEST_F(ServerSearchTest, searchResults)
 {
   const TestData testData[] = {
     {
@@ -1340,14 +1351,12 @@ TEST_F(ServerTest, searchResults)
       /* pagination */       {}
     },
 
-    // Only RayCharles is in English.
-    // [TODO] We should extend our test data to have another zim file in english returning results.
     {
        /* query */          "pattern=travel"
                             "&books.filter.lang=eng",
        /* start */            0,
        /* resultsPerPage */   10,
-       /* totalResultCount */ 1,
+       /* totalResultCount */ 2,
        /* firstResultIndex */ 1,
        /* results */          {
          SEARCH_RESULT(
@@ -1357,6 +1366,14 @@ TEST_F(ServerTest, searchResults)
            /*bookTitle*/  "Ray Charles",
            /*wordCount*/  "204"
          ),
+
+        SEARCH_RESULT(
+          /*link*/   "/ROOT/content/example/Wikibooks.html",
+          /*title*/  "Wikibooks",
+          /*snippet*/    R"SNIPPET(...<b>Travel</b> guide Wikidata Knowledge database Commons Media repository Meta Coordination MediaWiki MediaWiki software Phabricator MediaWiki bug tracker Wikimedia Labs MediaWiki development The Wikimedia Foundation is a non-profit organization that depends on your voluntarism and donations to operate. If you find Wikibooks or other projects hosted by the Wikimedia Foundation useful, please volunteer or make a donation. Your donations primarily helps to purchase server equipment, launch new projects......)SNIPPET",
+          /*bookTitle*/  "Wikibooks",
+          /*wordCount*/  "538"
+        )
       },
       /* pagination */       {}
     },