diff --git a/include/library.h b/include/library.h
index 3fefa140e..602cfb9fd 100644
--- a/include/library.h
+++ b/include/library.h
@@ -105,6 +105,12 @@ class Filter {
     Filter& acceptTags(const Tags& tags);
     Filter& rejectTags(const Tags& tags);
 
+    /**
+     *  Set the filter to only accept books in the specified category.
+     *
+     *  Multiple categories can be specified as a comma-separated list (in
+     *  which case a book in any of those categories will match).
+     */
     Filter& category(std::string category);
 
     /**
diff --git a/src/library.cpp b/src/library.cpp
index 4ce865b7f..6ee51602f 100644
--- a/src/library.cpp
+++ b/src/library.cpp
@@ -549,25 +549,30 @@ Xapian::Query nameQuery(const std::string& name)
   return Xapian::Query("XN" + normalizeText(name));
 }
 
-Xapian::Query categoryQuery(const std::string& category)
+Xapian::Query multipleParamQuery(const std::string& commaSeparatedList, const std::string& prefix)
 {
-  return Xapian::Query("XC" + normalizeText(category));
+  Xapian::Query q;
+  bool firstIteration = true;
+  for ( const auto& elem : kiwix::split(commaSeparatedList, ",") ) {
+    const Xapian::Query singleQuery(prefix + normalizeText(elem));
+    if ( firstIteration ) {
+      q = singleQuery;
+      firstIteration = false;
+    } else {
+      q = Xapian::Query(Xapian::Query::OP_OR, q, singleQuery);
+    }
+  }
+  return q;
+}
+
+Xapian::Query categoryQuery(const std::string& commaSeparatedCategoryList)
+{
+  return multipleParamQuery(commaSeparatedCategoryList, "XC");
 }
 
 Xapian::Query langQuery(const std::string& commaSeparatedLanguageList)
 {
-  Xapian::Query q;
-  bool firstIteration = true;
-  for ( const auto& lang : kiwix::split(commaSeparatedLanguageList, ",") ) {
-    const Xapian::Query singleLangQuery("L" + normalizeText(lang));
-    if ( firstIteration ) {
-      q = singleLangQuery;
-      firstIteration = false;
-    } else {
-      q = Xapian::Query(Xapian::Query::OP_OR, q, singleLangQuery);
-    }
-  }
-  return q;
+  return multipleParamQuery(commaSeparatedLanguageList, "L");
 }
 
 Xapian::Query publisherQuery(const std::string& publisher)
diff --git a/test/library_server.cpp b/test/library_server.cpp
index 2274ccf4c..c9c34e367 100644
--- a/test/library_server.cpp
+++ b/test/library_server.cpp
@@ -301,20 +301,41 @@ TEST_F(LibraryServerTest, catalog_search_by_tag)
 
 TEST_F(LibraryServerTest, catalog_search_by_category)
 {
-  const auto r = zfs1_->GET("/ROOT%23%3F/catalog/search?category=jazz");
-  EXPECT_EQ(r->status, 200);
-  EXPECT_EQ(maskVariableOPDSFeedData(r->body),
-    OPDS_FEED_TAG
-    "  <id>12345678-90ab-cdef-1234-567890abcdef</id>\n"
-    "  <title>Filtered zims (category=jazz)</title>\n"
-    "  <updated>YYYY-MM-DDThh:mm:ssZ</updated>\n"
-    "  <totalResults>1</totalResults>\n"
-    "  <startIndex>0</startIndex>\n"
-    "  <itemsPerPage>1</itemsPerPage>\n"
-    CATALOG_LINK_TAGS
-    CHARLES_RAY_CATALOG_ENTRY
-    "</feed>\n"
-  );
+
+  {
+    const auto r = zfs1_->GET("/ROOT%23%3F/catalog/search?category=jazz");
+    EXPECT_EQ(r->status, 200);
+    EXPECT_EQ(maskVariableOPDSFeedData(r->body),
+      OPDS_FEED_TAG
+      "  <id>12345678-90ab-cdef-1234-567890abcdef</id>\n"
+      "  <title>Filtered zims (category=jazz)</title>\n"
+      "  <updated>YYYY-MM-DDThh:mm:ssZ</updated>\n"
+      "  <totalResults>1</totalResults>\n"
+      "  <startIndex>0</startIndex>\n"
+      "  <itemsPerPage>1</itemsPerPage>\n"
+      CATALOG_LINK_TAGS
+      CHARLES_RAY_CATALOG_ENTRY
+      "</feed>\n"
+    );
+  }
+
+  {
+    const auto r = zfs1_->GET("/ROOT%23%3F/catalog/search?category=jazz,wikipedia");
+    EXPECT_EQ(r->status, 200);
+    EXPECT_EQ(maskVariableOPDSFeedData(r->body),
+      OPDS_FEED_TAG
+      "  <id>12345678-90ab-cdef-1234-567890abcdef</id>\n"
+      "  <title>Filtered zims (category=jazz%2Cwikipedia)</title>\n"
+      "  <updated>YYYY-MM-DDThh:mm:ssZ</updated>\n"
+      "  <totalResults>2</totalResults>\n"
+      "  <startIndex>0</startIndex>\n"
+      "  <itemsPerPage>2</itemsPerPage>\n"
+      CATALOG_LINK_TAGS
+      RAY_CHARLES_CATALOG_ENTRY
+      CHARLES_RAY_CATALOG_ENTRY
+      "</feed>\n"
+    );
+  }
 }
 
 TEST_F(LibraryServerTest, catalog_search_by_language)
@@ -793,6 +814,40 @@ TEST_F(LibraryServerTest, catalog_v2_entries_filtered_by_language)
   }
 }
 
+TEST_F(LibraryServerTest, catalog_v2_entries_filtered_by_category)
+{
+  {
+    const auto r = zfs1_->GET("/ROOT%23%3F/catalog/v2/entries?category=jazz");
+    EXPECT_EQ(r->status, 200);
+    EXPECT_EQ(maskVariableOPDSFeedData(r->body),
+      CATALOG_V2_ENTRIES_PREAMBLE("?category=jazz")
+      "  <title>Filtered Entries (category=jazz)</title>\n"
+      "  <updated>YYYY-MM-DDThh:mm:ssZ</updated>\n"
+      "  <totalResults>1</totalResults>\n"
+      "  <startIndex>0</startIndex>\n"
+      "  <itemsPerPage>1</itemsPerPage>\n"
+      CHARLES_RAY_CATALOG_ENTRY
+      "</feed>\n"
+    );
+  }
+
+  {
+    const auto r = zfs1_->GET("/ROOT%23%3F/catalog/v2/entries?category=jazz,wikipedia");
+    EXPECT_EQ(r->status, 200);
+    EXPECT_EQ(maskVariableOPDSFeedData(r->body),
+      CATALOG_V2_ENTRIES_PREAMBLE("?category=jazz%2Cwikipedia")
+      "  <title>Filtered Entries (category=jazz%2Cwikipedia)</title>\n"
+      "  <updated>YYYY-MM-DDThh:mm:ssZ</updated>\n"
+      "  <totalResults>2</totalResults>\n"
+      "  <startIndex>0</startIndex>\n"
+      "  <itemsPerPage>2</itemsPerPage>\n"
+      RAY_CHARLES_CATALOG_ENTRY
+      CHARLES_RAY_CATALOG_ENTRY
+      "</feed>\n"
+    );
+  }
+}
+
 TEST_F(LibraryServerTest, catalog_v2_entries_multiple_filters)
 {
   {