diff --git a/main/src/com/google/refine/importers/ExcelImporter.java b/main/src/com/google/refine/importers/ExcelImporter.java
index 7ef471a48..802344bcc 100644
--- a/main/src/com/google/refine/importers/ExcelImporter.java
+++ b/main/src/com/google/refine/importers/ExcelImporter.java
@@ -43,6 +43,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import org.apache.poi.POIXMLException;
 import org.apache.poi.common.usermodel.Hyperlink;
 import org.apache.poi.hssf.usermodel.HSSFDateUtil;
 import org.apache.poi.hssf.usermodel.HSSFWorkbook;
@@ -117,6 +118,8 @@ public class ExcelImporter extends TabularImportingParserBase {
             logger.error("Error generating parser UI initialization data for Excel file", e);
         } catch (IllegalArgumentException e) {
             logger.error("Error generating parser UI initialization data for Excel file (only Excel 97 & later supported)", e);
+        } catch (POIXMLException e) {
+            logger.error("Error generating parser UI initialization data for Excel file - invalid XML", e);
         }
         
         return options;
@@ -162,6 +165,13 @@ public class ExcelImporter extends TabularImportingParserBase {
                     e
                 ));
                 return;
+        } catch (POIXMLException e) {
+            exceptions.add(new ImportException(
+                    "Attempted to parse as an Excel file but failed. " +
+                    "Invalid XML.",
+                    e
+                ));
+                return;
         }
         
         int[] sheets = JSONUtilities.getIntArray(options, "sheets");
diff --git a/main/src/com/google/refine/importers/RdfTripleImporter.java b/main/src/com/google/refine/importers/RdfTripleImporter.java
index bfa22bc4a..ed9d7dbae 100644
--- a/main/src/com/google/refine/importers/RdfTripleImporter.java
+++ b/main/src/com/google/refine/importers/RdfTripleImporter.java
@@ -86,18 +86,23 @@ public class RdfTripleImporter extends ImportingParserBase {
             JSONObject options, List<Exception> exceptions) {
         
         Graph graph;
-        switch (mode) {
-        case NT:
-            graph = rdfReader.parseNTriples(input);
-            break;
-        case N3:
-            graph = rdfReader.parseN3(input);
-            break;
-        case RDFXML:
-            graph = rdfReader.parseRdfXml(input);             
-            break;
-        default:
-            throw new IllegalArgumentException("Unknown parsing mode");    
+        try {
+            switch (mode) {
+            case NT:
+                graph = rdfReader.parseNTriples(input);
+                break;
+            case N3:
+                graph = rdfReader.parseN3(input);
+                break;
+            case RDFXML:
+                graph = rdfReader.parseRdfXml(input);             
+                break;
+            default:
+                throw new IllegalArgumentException("Unknown parsing mode");    
+            }
+        } catch (Exception e) {
+            exceptions.add(e);
+            return;
         }
         
         ClosableIterable<Triple> triples = graph.find(ANY_SUBJECT_NODE, ANY_PREDICATE_NODE, ANY_OBJECT_NODE);