diff --git a/src/gtk/tbargtk.cpp b/src/gtk/tbargtk.cpp
index 496fa62618..0802257ccc 100644
--- a/src/gtk/tbargtk.cpp
+++ b/src/gtk/tbargtk.cpp
@@ -258,6 +258,8 @@ void wxToolBar::Init()
     m_bg = (GdkColor *)NULL;
     m_toolbar = (GtkToolbar *)NULL;
     m_blockEvent = FALSE;
+    m_defaultWidth = 32;
+    m_defaultHeight = 32;
 }
 
 wxToolBar::~wxToolBar()
diff --git a/src/gtk1/tbargtk.cpp b/src/gtk1/tbargtk.cpp
index 496fa62618..0802257ccc 100644
--- a/src/gtk1/tbargtk.cpp
+++ b/src/gtk1/tbargtk.cpp
@@ -258,6 +258,8 @@ void wxToolBar::Init()
     m_bg = (GdkColor *)NULL;
     m_toolbar = (GtkToolbar *)NULL;
     m_blockEvent = FALSE;
+    m_defaultWidth = 32;
+    m_defaultHeight = 32;
 }
 
 wxToolBar::~wxToolBar()