diff --git a/extensions/wikidata/module/langs/translation-en.json b/extensions/wikidata/module/langs/translation-en.json
index b7be57aca..70c396c90 100644
--- a/extensions/wikidata/module/langs/translation-en.json
+++ b/extensions/wikidata/module/langs/translation-en.json
@@ -193,6 +193,10 @@
                 "non-printable-characters": {
                         "title": "Non-printable characters in strings.",
                         "body": "Strings such as <span class=\"wb-issue-preformat\">{example_string}</span> contain non-printable characters."
+                },
+                "invalid-identifier-space": {
+                        "title": "Invalid identifier space for reconciled cells.",
+                        "body": "Some reconciled cells such as <span class=\"wb-issue-preformat\">{example_cell}</span> were ignored because they are not reconciled to Wikidata."
                 }
        }
 }
diff --git a/extensions/wikidata/src/org/openrefine/wikidata/schema/WbItemVariable.java b/extensions/wikidata/src/org/openrefine/wikidata/schema/WbItemVariable.java
index 599f0e551..00c634580 100644
--- a/extensions/wikidata/src/org/openrefine/wikidata/schema/WbItemVariable.java
+++ b/extensions/wikidata/src/org/openrefine/wikidata/schema/WbItemVariable.java
@@ -23,8 +23,10 @@
  ******************************************************************************/
 package org.openrefine.wikidata.schema;
 
+import org.openrefine.wikidata.qa.QAWarning;
 import org.openrefine.wikidata.schema.entityvalues.ReconItemIdValue;
 import org.openrefine.wikidata.schema.exceptions.SkipSchemaExpressionException;
+import org.wikidata.wdtk.datamodel.helpers.Datamodel;
 import org.wikidata.wdtk.datamodel.interfaces.ItemIdValue;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
@@ -61,6 +63,12 @@ public class WbItemVariable extends WbVariableExpr<ItemIdValue> {
             throws SkipSchemaExpressionException {
         if (cell.recon != null
                 && (Judgment.Matched.equals(cell.recon.judgment) || Judgment.New.equals(cell.recon.judgment))) {
+            if (!cell.recon.identifierSpace.equals(Datamodel.SITE_WIKIDATA)) {
+                QAWarning warning = new QAWarning("invalid-identifier-space", null, QAWarning.Severity.INFO, 1);
+                warning.setProperty("example_cell", cell.value.toString());
+                ctxt.addWarning(warning);
+                throw new SkipSchemaExpressionException();
+            }
             return new ReconItemIdValue(cell.recon, cell.value.toString());
         }
         throw new SkipSchemaExpressionException();
diff --git a/extensions/wikidata/tests/src/org/openrefine/wikidata/schema/WbItemVariableTest.java b/extensions/wikidata/tests/src/org/openrefine/wikidata/schema/WbItemVariableTest.java
index de19a8aff..8533ea0c9 100644
--- a/extensions/wikidata/tests/src/org/openrefine/wikidata/schema/WbItemVariableTest.java
+++ b/extensions/wikidata/tests/src/org/openrefine/wikidata/schema/WbItemVariableTest.java
@@ -67,6 +67,16 @@ public class WbItemVariableTest extends WbVariableTest<ItemIdValue> {
         Cell cell = new Cell("some value", recon);
         isSkipped(cell);
     }
+    
+    @Test
+    public void testInvalidSpace() {
+        Recon recon = Recon.makeWikidataRecon(34989L);
+        recon.identifierSpace = "http://my.own.wikiba.se/";
+        recon.candidates = Collections.singletonList(new ReconCandidate("Q123", "some item", null, 100.0));
+        recon.judgment = Recon.Judgment.Matched;
+        Cell cell = new Cell("some value", recon);
+        isSkipped(cell);
+    }
 
     @Test
     public void testUnreconciledCell() {