diff --git a/README.md b/README.md
index d558049..f6e0c80 100644
--- a/README.md
+++ b/README.md
@@ -727,6 +727,16 @@ Possible values are `true` and `false`. Defaults to `false`.
 
 Note that if set to `true`, the indexes may be out-of-date if data has changed in the application while mu-search was down.
 
+#### Prefixes
+You can define default prefixes, e.g:
+```json
+prefixes: [
+    {
+        "rdfs": "http://data.vlaanderen.be/ns/besluit#",
+    }    
+]
+
+```
 #### Eager indexes
 Configure indexes to be pre-built when the application starts. For each user search profile for which the indexes needs to be prepared, the authorization group names and their corresponding variables needs to be passed.
 
diff --git a/config/config.json b/config/config.json
index 6c0b28b..872d30e 100644
--- a/config/config.json
+++ b/config/config.json
@@ -1,21 +1,48 @@
 {
     "batch_size": 12,
     "max_batches": 1,
-    "automatic_index_updates" : true ,
-    "eager_indexing_groups" : [[{"name" : "documents", "variables" : ["human"]}],
-                               [{"name" : "documents", "variables" : ["chicken"]}]],
-    "attachments_path_base" : "/local/files/directory",
-    "persist_indexes" : false,
-    "default_settings" : {
+    "automatic_index_updates": true,
+    "eager_indexing_groups": [
+        [
+            {
+                "name": "documents",
+                "variables": [
+                    "human"
+                ]
+            }
+        ],
+        [
+            {
+                "name": "documents",
+                "variables": [
+                    "chicken"
+                ]
+            }
+        ]
+    ],
+    "attachments_path_base": "/local/files/directory",
+    "persist_indexes": false,
+    "prefixes": [],
+    "default_settings": {
         "analysis": {
-          "analyzer": {
-            "dutchanalyzer": {
-              "tokenizer": "standard",
-              "filter": ["lowercase", "asciifolding", "dutchstemmer"] } },
-          "filter": {
-            "dutchstemmer": {
-              "type": "stemmer",
-              "name": "dutch" } } } },
+            "analyzer": {
+                "dutchanalyzer": {
+                    "tokenizer": "standard",
+                    "filter": [
+                        "lowercase",
+                        "asciifolding",
+                        "dutchstemmer"
+                    ]
+                }
+            },
+            "filter": {
+                "dutchstemmer": {
+                    "type": "stemmer",
+                    "name": "dutch"
+                }
+            }
+        }
+    },
     "types": [
         {
             "type": "document",
@@ -23,13 +50,13 @@
             "rdf_type": "http://example.org/Document",
             "properties": {
                 "title": "http://purl.org/dc/elements/1.1/title",
-                "description": "http://purl.org/dc/elements/1.1/description" ,
-                "data" : {
-                    "via" : [
+                "description": "http://purl.org/dc/elements/1.1/description",
+                "data": {
+                    "via": [
                         "http://mu.semte.ch/vocabularies/ext/file",
                         "^http://www.semanticdesktop.org/ontologies/2007/01/19/nie#dataSource"
                     ],
-                    "attachment_pipeline" : "attachment"
+                    "attachment_pipeline": "attachment"
                 }
             },
             "mappings": null
@@ -45,8 +72,11 @@
             "mappings": null
         },
         {
-            "type" : "userdoc",
-            "composite_types": ["document", "user"],
+            "type": "userdoc",
+            "composite_types": [
+                "document",
+                "user"
+            ],
             "on_path": "userdocs",
             "properties": [
                 {
diff --git a/lib/mu_search/config_parser.rb b/lib/mu_search/config_parser.rb
index 8979549..600148c 100644
--- a/lib/mu_search/config_parser.rb
+++ b/lib/mu_search/config_parser.rb
@@ -16,7 +16,8 @@ def self.parse(path)
         eager_indexing_groups: [],
         update_wait_interval_minutes: 1,
         number_of_threads: 1,
-        enable_raw_dsl_endpoint: false
+        enable_raw_dsl_endpoint: false,
+        prefixes: []
       }
 
       json_config = JSON.parse(File.read(path))
@@ -48,6 +49,7 @@ def self.parse(path)
         config[:eager_indexing_groups] = json_config["eager_indexing_groups"]
       end
 
+      config[:prefixes] = json_config["prefixes"]
       config[:type_definitions] = Hash[MuSearch::IndexDefinition.from_json_config(json_config["types"])]
       config
     end
diff --git a/lib/mu_search/sparql.rb b/lib/mu_search/sparql.rb
index 6a0e583..0663724 100644
--- a/lib/mu_search/sparql.rb
+++ b/lib/mu_search/sparql.rb
@@ -3,18 +3,20 @@
 module MuSearch
   module SPARQL
     class ClientWrapper
-      def initialize(logger:, sparql_client:, options:)
+      def initialize(logger:, sparql_client:, options:, prefixes:)
         @logger = logger
         @sparql_client = sparql_client
         @options = options
       end
 
       def query(query_string)
+        query_string = @prefixes + "\n" + query_string
         @logger.debug("SPARQL") { "Executing query with #{@options.inspect}\n#{query_string}" }
         @sparql_client.query query_string, @options
       end
 
       def update(query_string)
+        query_string = @prefixes + "\n" + query_string
         @logger.debug("SPARQL") { "Executing update with #{@options.inspect}\n#{query_string}" }
         @sparql_client.update query_string, @options
       end
@@ -25,7 +27,8 @@ class ConnectionPool
       # default number of threads to use for indexing and update handling
       DEFAULT_NUMBER_OF_THREADS = 2
 
-      def initialize(logger:, number_of_threads:)
+      def initialize(logger:, number_of_threads:, prefixes:)
+        @prefixes = prefixes.map {|key, value| "prefix #{key}: <#{value}>"} .join("\n")
         @logger = logger
         number_of_threads = DEFAULT_NUMBER_OF_THREADS if number_of_threads <= 0
         @sparql_connection_pool = ::ConnectionPool.new(size: number_of_threads, timeout: 3) do
@@ -106,7 +109,7 @@ def with_sudo(&block)
       def with_options(sparql_options)
         @sparql_connection_pool.with do |sparql_client|
           @logger.debug("SPARQL") { "Claimed connection from pool. There are #{@sparql_connection_pool.available} connections left" }
-          client_wrapper = ClientWrapper.new(logger: @logger, sparql_client: sparql_client, options: sparql_options)
+          client_wrapper = ClientWrapper.new(logger: @logger, sparql_client: sparql_client, options: sparql_options, prefixes: @prefixes)
           yield client_wrapper
         end
       end
diff --git a/web.rb b/web.rb
index 68c8afa..bb54281 100644
--- a/web.rb
+++ b/web.rb
@@ -119,6 +119,7 @@ def setup_delta_handling(index_manager, elasticsearch, tika, sparql_connection_p
 
   sparql_connection_pool = MuSearch::SPARQL::ConnectionPool.new(
     number_of_threads: configuration[:number_of_threads],
+    prefixes: configuration[:prefixes],
     logger: SinatraTemplate::Utils.log
   )