diff --git a/src/main/java/fr/igred/omero/annotations/TableWrapper.java b/src/main/java/fr/igred/omero/annotations/TableWrapper.java
index a445f64b..2526262c 100644
--- a/src/main/java/fr/igred/omero/annotations/TableWrapper.java
+++ b/src/main/java/fr/igred/omero/annotations/TableWrapper.java
@@ -43,6 +43,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ExecutionException;
@@ -394,18 +395,18 @@ private static ROIData[] createROIColumn(ResultsTable results,
                                                                            safeParseLong(r.getProperty(roiIdProperty))))
                                                .filter(p -> p.getKey() != null)
                                                .filter(p -> p.getValue() != null)
-                                               .collect(toMap(SimpleEntry::getKey,
-                                                              p -> id2roi.get(p.getValue()),
-                                                              (x1, x2) -> x1));
+                                               .collect(HashMap::new,
+                                                        (m, v) -> m.put(v.getKey(), id2roi.get(v.getValue())),
+                                                        HashMap::putAll);
 
         Map<String, ROIData> shape2roi = ijRois.stream()
                                                .map(r -> new SimpleEntry<>(r.getName(),
                                                                            safeParseLong(r.getProperty(roiIdProperty))))
                                                .filter(p -> p.getKey() != null)
                                                .filter(p -> p.getValue() != null)
-                                               .collect(toMap(SimpleEntry::getKey,
-                                                              p -> id2roi.get(p.getValue()),
-                                                              (x1, x2) -> x1));
+                                               .collect(HashMap::new,
+                                                        (m, v) -> m.put(v.getKey(), id2roi.get(v.getValue())),
+                                                        HashMap::putAll);
         String colToDelete = "";
         if (results.columnExists(roiIdProperty)) {
             Variable[] roiCol = results.getColumnAsVariables(roiIdProperty);
@@ -440,6 +441,20 @@ private static ROIData[] createROIColumn(ResultsTable results,
     }
 
 
+    /**
+     * Checks if the new columns match the existing ones.
+     *
+     * @param nColumns The number of columns in the current Results Table.
+     * @param offset   The offset in the current Results Table.
+     */
+    private boolean checkColumns(int nColumns, int offset) {
+        boolean match = offset + nColumns == columnCount;
+        if (offset > 0 && !columns[0].getType().equals(ImageData.class)) match = false;
+        if (offset > 1 && !columns[1].getType().equals(ROIData.class)) match = false;
+        return match;
+    }
+
+
     /**
      * Sets the information about a given column.
      *
@@ -522,8 +537,8 @@ public void addRows(Client client, ResultsTable results, Long imageId, List<? ex
         String[] headings = rt.getHeadings();
 
         int nColumns = headings.length;
-        if (nColumns + offset != columnCount) {
-            throw new IllegalArgumentException("Number of columns mismatch");
+        if (!checkColumns(nColumns, offset)) {
+            throw new IllegalArgumentException("Number or type of columns mismatch");
         }
 
         int n = rt.size();
diff --git a/src/test/java/fr/igred/omero/annotations/ImageJTableTest.java b/src/test/java/fr/igred/omero/annotations/ImageJTableTest.java
index e689aacd..172e4fe5 100644
--- a/src/test/java/fr/igred/omero/annotations/ImageJTableTest.java
+++ b/src/test/java/fr/igred/omero/annotations/ImageJTableTest.java
@@ -45,6 +45,7 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assumptions.assumeFalse;
 
@@ -722,4 +723,41 @@ void testSaveTableAs() throws Exception {
         Files.deleteIfExists(file.toPath());
     }
 
+
+    @Test
+    void testAddRowsWithMismatch() throws Exception {
+        List<ROIWrapper> rois = new ArrayList<>(2);
+        rois.add(new ROIWrapper());
+        rois.add(new ROIWrapper());
+
+        rois.get(0).setImage(image);
+        rois.get(1).setImage(image);
+
+        for (int i = 0; i < 4; i++) {
+            RectangleWrapper rectangle = new RectangleWrapper();
+            rectangle.setText(String.valueOf(10 + i % 2));
+            rectangle.setCoordinates(i * 2, i * 2, 10, 10);
+            rectangle.setZ(i);
+            rectangle.setT(0);
+            rectangle.setC(0);
+
+            if (i % 2 == 1) rois.get(0).addShape(rectangle);
+            else rois.get(1).addShape(rectangle);
+        }
+
+        List<ROIWrapper> newROIs = image.saveROIs(client, rois);
+        List<Roi>        ijRois  = ROIWrapper.toImageJ(newROIs);
+
+        String label1 = image.getName() + ":" + newROIs.get(0).getShapes().get(0).getText() + ":4";
+        String label2 = image.getName() + ":" + newROIs.get(1).getShapes().get(0).getText() + ":10";
+
+        ResultsTable results1 = createOneRowResultsTable(label1, volume1, unit1);
+        ResultsTable results2 = createOneRowResultsTable(label2, volume2, unit2);
+
+        TableWrapper table = new TableWrapper(client, results1, IMAGE1.id, ijRois);
+
+        assertThrows(IllegalArgumentException.class,
+                     () -> table.addRows(client, results2, null, ijRois));
+    }
+
 }
\ No newline at end of file