diff --git a/CHANGELOG.md b/CHANGELOG.md
index f32e145..10a18f4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # PythonQwt Releases
 
+## Version 0.12.7
+
+- Fixed other random crashes (segfaults) on Linux related to Qt objects stored in
+  private data structures (`QwtGraphic_PrivateData`, `QwtLegendLabel_PrivateData`)
+
 ## Version 0.12.6
 
 - Fixed random crashes (segfaults) on Linux related to Qt objects stored in cache data
diff --git a/qwt/graphic.py b/qwt/graphic.py
index 1eccc34..51bfd13 100644
--- a/qwt/graphic.py
+++ b/qwt/graphic.py
@@ -187,10 +187,10 @@ def scaleFactorY(self, pathRect, targetRect, scalePens):
 
 class QwtGraphic_PrivateData(object):
     def __init__(self):
-        self.boundingRect = QRectF(0.0, 0.0, -1.0, -1.0)
-        self.pointRect = QRectF(0.0, 0.0, -1.0, -1.0)
+        self.boundingRect = None
+        self.pointRect = None
         self.initialTransform = None
-        self.defaultSize = QSizeF()
+        self.defaultSize = None
         self.commands = []
         self.pathInfos = []
         self.renderHints = 0
@@ -286,9 +286,9 @@ def reset(self):
         """Clear all stored commands"""
         self.__data.commands = []
         self.__data.pathInfos = []
-        self.__data.boundingRect = QRectF(0.0, 0.0, -1.0, -1.0)
-        self.__data.pointRect = QRectF(0.0, 0.0, -1.0, -1.0)
-        self.__data.defaultSize = QSizeF()
+        self.__data.boundingRect = None
+        self.__data.pointRect = None
+        self.__data.defaultSize = None
 
     def isNull(self):
         """Return True, when no painter commands have been stored"""
@@ -296,7 +296,7 @@ def isNull(self):
 
     def isEmpty(self):
         """Return True, when the bounding rectangle is empty"""
-        return self.__data.boundingRect.isEmpty()
+        return self.__data.boundingRect is None or self.__data.boundingRect.isEmpty()
 
     def setRenderHint(self, hint, on=True):
         """Toggle an render hint"""
@@ -321,7 +321,7 @@ def boundingRect(self):
 
             :py:meth:`controlPointRect`, :py:meth:`scaledBoundingRect`
         """
-        if self.__data.boundingRect.width() < 0:
+        if self.__data.boundingRect is None:
             return QRectF()
         return self.__data.boundingRect
 
@@ -337,7 +337,7 @@ def controlPointRect(self):
 
             :py:meth:`boundingRect()`, :py:meth:`scaledBoundingRect()`
         """
-        if self.__data.pointRect.width() < 0:
+        if self.__data.pointRect is None:
             return QRectF()
         return self.__data.pointRect
 
@@ -407,7 +407,7 @@ def defaultSize(self):
 
             :py:meth:`setDefaultSize()`, :py:meth:`boundingRect()`
         """
-        if not self.__data.defaultSize.isEmpty():
+        if self.__data.defaultSize is not None:
             return self.__data.defaultSize
         return self.boundingRect().size()
 
@@ -486,9 +486,9 @@ def render(self, *args):
                 return
             sx = 1.0
             sy = 1.0
-            if self.__data.pointRect.width() > 0.0:
+            if self.__data.pointRect is not None:
                 sx = rect.width() / self.__data.pointRect.width()
-            if self.__data.pointRect.height() > 0.0:
+            if self.__data.pointRect is not None:
                 sy = rect.height() / self.__data.pointRect.height()
             scalePens = not bool(self.__data.renderHints & self.RenderPensUnscaled)
             for info in self.__data.pathInfos:
@@ -741,13 +741,13 @@ def updateBoundingRect(self, rect):
             cr = painter.clipRegion().boundingRect()
             cr = painter.transform().mapRect(cr)
             br &= cr
-        if self.__data.boundingRect.width() < 0:
+        if self.__data.boundingRect is None:
             self.__data.boundingRect = br
         else:
             self.__data.boundingRect |= br
 
     def updateControlPointRect(self, rect):
-        if self.__data.pointRect.width() < 0.0:
+        if self.__data.pointRect is None:
             self.__data.pointRect = rect
         else:
             self.__data.pointRect |= rect
diff --git a/qwt/legend.py b/qwt/legend.py
index 86030c3..5b516d3 100644
--- a/qwt/legend.py
+++ b/qwt/legend.py
@@ -176,7 +176,7 @@ def __init__(self):
         self.isDown = False
         self.spacing = MARGIN
         self.legendData = QwtLegendData()
-        self.icon = QPixmap()
+        self.icon = None
 
 
 class QwtLegendLabel(QwtTextLabel):
@@ -294,7 +294,7 @@ def icon(self):
 
             :py:meth:`setIcon()`
         """
-        return self.__data.icon
+        return QPixmap() if self.__data.icon is None else self.__data.icon
 
     def setSpacing(self, spacing):
         """
@@ -312,7 +312,7 @@ def setSpacing(self, spacing):
             mgn = self.contentsMargins()
             margin = max([mgn.left(), mgn.top(), mgn.right(), mgn.bottom()])
             indent = margin + self.__data.spacing
-            if self.__data.icon.width() > 0:
+            if self.__data.icon is not None:
                 indent += self.__data.icon.width() + self.__data.spacing
             self.setIndent(indent)
 
@@ -409,7 +409,7 @@ def paintEvent(self, e):
             painter.translate(shiftSize.width(), shiftSize.height())
         painter.setClipRect(cr)
         self.drawContents(painter)
-        if not self.__data.icon.isNull():
+        if self.__data.icon is not None:
             iconRect = QRect(cr)
             iconRect.setX(iconRect.x() + self.margin())
             if self.__data.itemMode != QwtLegendData.ReadOnly: