diff --git a/python/plugins/processing/gui/AlgorithmLocatorFilter.py b/python/plugins/processing/gui/AlgorithmLocatorFilter.py
index 2387c6760ae..38a8c83b546 100755
--- a/python/plugins/processing/gui/AlgorithmLocatorFilter.py
+++ b/python/plugins/processing/gui/AlgorithmLocatorFilter.py
@@ -88,6 +88,9 @@ class AlgorithmLocatorFilter(QgsLocatorFilter):
             prevMapTool = canvas.mapTool()
             dlg.show()
             dlg.exec_()
+            # have to manually delete the dialog - otherwise it's owned by the
+            # iface mainWindow and never deleted
+            del dlg
             if canvas.mapTool() != prevMapTool:
                 try:
                     canvas.mapTool().reset()
diff --git a/python/plugins/processing/gui/ProcessingToolbox.py b/python/plugins/processing/gui/ProcessingToolbox.py
index 555c0ff484b..074e71dea75 100644
--- a/python/plugins/processing/gui/ProcessingToolbox.py
+++ b/python/plugins/processing/gui/ProcessingToolbox.py
@@ -250,6 +250,9 @@ class ProcessingToolbox(BASE, WIDGET):
                 dlg = BatchAlgorithmDialog(alg)
                 dlg.show()
                 dlg.exec_()
+                # have to manually delete the dialog - otherwise it's owned by the
+                # iface mainWindow and never deleted
+                del dlg
 
     def executeAlgorithm(self):
         item = self.algorithmTree.currentItem()
@@ -288,6 +291,9 @@ class ProcessingToolbox(BASE, WIDGET):
                         ProcessingConfig.SHOW_RECENT_ALGORITHMS)
                     if showRecent:
                         self.addRecentAlgorithms(True)
+                # have to manually delete the dialog - otherwise it's owned by the
+                # iface mainWindow and never deleted
+                del dlg
             else:
                 feedback = MessageBarProgress()
                 context = dataobjects.createContext(feedback)
diff --git a/python/plugins/processing/gui/ScriptEditorDialog.py b/python/plugins/processing/gui/ScriptEditorDialog.py
index 3abccb0f022..cb2d85266fa 100644
--- a/python/plugins/processing/gui/ScriptEditorDialog.py
+++ b/python/plugins/processing/gui/ScriptEditorDialog.py
@@ -279,6 +279,10 @@ class ScriptEditorDialog(BASE, WIDGET):
         dlg.show()
         dlg.exec_()
 
+        # have to manually delete the dialog - otherwise it's owned by the
+        # iface mainWindow and never deleted
+        del dlg
+
         if canvas.mapTool() != prevMapTool:
             try:
                 canvas.mapTool().reset()
diff --git a/python/plugins/processing/gui/menus.py b/python/plugins/processing/gui/menus.py
index c9164a2978f..02d4f9e4f1e 100644
--- a/python/plugins/processing/gui/menus.py
+++ b/python/plugins/processing/gui/menus.py
@@ -211,6 +211,9 @@ def _executeAlgorithm(alg):
         prevMapTool = canvas.mapTool()
         dlg.show()
         dlg.exec_()
+        # have to manually delete the dialog - otherwise it's owned by the
+        # iface mainWindow and never deleted
+        del dlg
         if canvas.mapTool() != prevMapTool:
             try:
                 canvas.mapTool().reset()
diff --git a/python/plugins/processing/modeler/ModelerDialog.py b/python/plugins/processing/modeler/ModelerDialog.py
index 4a7089f7688..3fe67981723 100644
--- a/python/plugins/processing/modeler/ModelerDialog.py
+++ b/python/plugins/processing/modeler/ModelerDialog.py
@@ -291,6 +291,9 @@ class ModelerDialog(BASE, WIDGET):
 
         dlg = AlgorithmDialog(self.model)
         dlg.exec_()
+        # have to manually delete the dialog - otherwise it's owned by the
+        # iface mainWindow and never deleted
+        del dlg
 
     def save(self):
         self.saveModel(False)