diff --git a/src/db/db/dbCIFReader.cc b/src/db/db/dbCIFReader.cc
index ac4ba4940..30ddf3781 100644
--- a/src/db/db/dbCIFReader.cc
+++ b/src/db/db/dbCIFReader.cc
@@ -449,6 +449,9 @@ CIFReader::read_cell (db::Layout &layout, db::Cell &cell, double sf, int level)
         if (! test_semi ()) {
           denom = read_integer ();
           divider = read_integer ();
+          if (divider == 0) {
+            error ("'DS' command: divider cannot be zero");
+          }
         }
 
         expect_semi ();
@@ -476,7 +479,7 @@ CIFReader::read_cell (db::Layout &layout, db::Cell &cell, double sf, int level)
         // DF command:
         // "D" blank* "F"
         if (level == 0) {
-          error ("'DS' command must be inside a cell specification");
+          error ("'DF' command must be inside a cell specification");
         } 
 
         //  skip the rest of the command
@@ -490,7 +493,7 @@ CIFReader::read_cell (db::Layout &layout, db::Cell &cell, double sf, int level)
         //  "D" blank* "D" integer
 
         read_integer ();
-        warn ("DD command ignored");
+        warn ("'DD' command ignored");
         skip_to_end ();
 
       } else {
diff --git a/src/db/db/dbOASISWriter.cc b/src/db/db/dbOASISWriter.cc
index c7620e051..ba2e2546e 100644
--- a/src/db/db/dbOASISWriter.cc
+++ b/src/db/db/dbOASISWriter.cc
@@ -665,6 +665,9 @@ OASISWriter::OASISWriter ()
     mp_cell (0),
     m_layer (0), m_datatype (0),
     m_in_cblock (false),
+    m_propname_id (0),
+    m_propstring_id (0),
+    m_proptables_written (false),
     m_progress (tl::to_string (QObject::tr ("Writing OASIS file")), 10000)
 {
   m_progress.set_format (tl::to_string (QObject::tr ("%.0f MB")));
diff --git a/src/db/db/dbRecursiveShapeIterator.cc b/src/db/db/dbRecursiveShapeIterator.cc
index 7281b9861..c9797f858 100644
--- a/src/db/db/dbRecursiveShapeIterator.cc
+++ b/src/db/db/dbRecursiveShapeIterator.cc
@@ -104,6 +104,8 @@ RecursiveShapeIterator::RecursiveShapeIterator ()
   mp_shape_prop_sel = 0;
   m_shape_inv_prop_sel = false;
   m_needs_reinit = false;
+  m_inst_quad_id = 0;
+  m_shape_quad_id = 0;
 }
 
 RecursiveShapeIterator::RecursiveShapeIterator (const shapes_type &shapes)
diff --git a/src/db/db/gsiDeclDbLayoutDiff.cc b/src/db/db/gsiDeclDbLayoutDiff.cc
index 00f8e4cdd..10f3a58f0 100644
--- a/src/db/db/gsiDeclDbLayoutDiff.cc
+++ b/src/db/db/gsiDeclDbLayoutDiff.cc
@@ -36,7 +36,8 @@ class LayoutDiff
 {
 public:
   LayoutDiff ()
-    : mp_layout_a (0), mp_layout_b (0)
+    : mp_layout_a (0), mp_cell_a (0), m_layer_index_a (0),
+      mp_layout_b (0), mp_cell_b (0), m_layer_index_b (0)
   {
     // .. nothing yet ..
   }
diff --git a/src/db/unit_tests/dbObject.cc b/src/db/unit_tests/dbObject.cc
index a8d03d968..e341554d8 100644
--- a/src/db/unit_tests/dbObject.cc
+++ b/src/db/unit_tests/dbObject.cc
@@ -49,13 +49,13 @@ struct A : public db::Object
     x += d;
   }
   
-  void undo (db::Op *op) throw ()
+  void undo (db::Op *op)
   {
     AO *aop = dynamic_cast<AO *> (op);
     x -= aop->d;
   }
 
-  void redo (db::Op *op) throw ()
+  void redo (db::Op *op)
   {
     AO *aop = dynamic_cast<AO *> (op);
     tl_assert (aop != 0);
@@ -154,13 +154,13 @@ struct B : public db::Object
     }
   }
   
-  void undo (db::Op *op) throw ()
+  void undo (db::Op *op)
   {
     BO *bop = dynamic_cast<BO *> (op);
     x -= bop->d;
   }
 
-  void redo (db::Op *op) throw ()
+  void redo (db::Op *op)
   {
     BO *bop = dynamic_cast<BO *> (op);
     tl_assert (bop != 0);
diff --git a/src/lay/lay/laySearchReplaceDialog.cc b/src/lay/lay/laySearchReplaceDialog.cc
index de1880ffa..89104ddc0 100644
--- a/src/lay/lay/laySearchReplaceDialog.cc
+++ b/src/lay/lay/laySearchReplaceDialog.cc
@@ -703,7 +703,8 @@ SearchReplaceDialog::SearchReplaceDialog (lay::PluginRoot *root, lay::LayoutView
     m_current_mode (0),
     m_window (FitMarker),
     m_window_dim (0.0),
-    m_max_item_count (0)
+    m_max_item_count (0),
+    m_last_query_cv_index (0)
 {
   setObjectName (QString::fromUtf8 ("search_replace_dialog"));
 
diff --git a/src/laybasic/laybasic/layRedrawThreadWorker.cc b/src/laybasic/laybasic/layRedrawThreadWorker.cc
index d7a6fdd7d..7d67986e4 100644
--- a/src/laybasic/laybasic/layRedrawThreadWorker.cc
+++ b/src/laybasic/laybasic/layRedrawThreadWorker.cc
@@ -1143,7 +1143,7 @@ static bool
 skip_quad (const db::Box &qb, const lay::Bitmap *vertex_bitmap, const db::CplxTrans &trans)
 {
   double threshold = 32 / trans.mag (); // don't check cells below 32x32 pixels
-  if (qb.empty () || qb.width () > threshold || qb.height () > threshold) {
+  if (qb.empty () || qb.width () > threshold || qb.height () > threshold || !vertex_bitmap) {
     return false;
   }
 
diff --git a/src/laybasic/laybasic/laySaveLayoutOptionsDialog.cc b/src/laybasic/laybasic/laySaveLayoutOptionsDialog.cc
index 8e87d8e1c..4d7e6d1e4 100644
--- a/src/laybasic/laybasic/laySaveLayoutOptionsDialog.cc
+++ b/src/laybasic/laybasic/laySaveLayoutOptionsDialog.cc
@@ -321,7 +321,7 @@ SaveLayoutOptionsDialog::get_options_internal ()
 //  SaveLayoutAsOptionsDialog implementation
 
 SaveLayoutAsOptionsDialog::SaveLayoutAsOptionsDialog (QWidget *parent, const std::string &title)
-  : QDialog (parent), Ui::SaveLayoutAsOptionsDialog ()
+  : QDialog (parent), Ui::SaveLayoutAsOptionsDialog (), mp_tech (0)
 {
   setObjectName (QString::fromUtf8 ("save_layout_options_dialog"));
 
diff --git a/src/laybasic/laybasic/rdbMarkerBrowserPage.cc b/src/laybasic/laybasic/rdbMarkerBrowserPage.cc
index 61c2a30e4..c43b5d060 100644
--- a/src/laybasic/laybasic/rdbMarkerBrowserPage.cc
+++ b/src/laybasic/laybasic/rdbMarkerBrowserPage.cc
@@ -401,7 +401,7 @@ public:
   bool cat_matches (const QModelIndex &index, const QString &filter) const
   {
     MarkerBrowserTreeViewModelCacheEntry *node = (MarkerBrowserTreeViewModelCacheEntry *)(index.internalPointer ());
-    if (node) {
+    if (node && mp_database) {
 
       rdb::id_type id = node->id ();
       const rdb::Category *category = mp_database->category_by_id (id);
@@ -418,7 +418,7 @@ public:
   bool cell_matches (const QModelIndex &index, const QString &filter) const
   {
     MarkerBrowserTreeViewModelCacheEntry *node = (MarkerBrowserTreeViewModelCacheEntry *)(index.internalPointer ());
-    if (node) {
+    if (node && mp_database) {
 
       rdb::id_type id = node->id ();
       const rdb::Cell *cell = mp_database->cell_by_id (id);
@@ -435,7 +435,7 @@ public:
   bool no_errors (const QModelIndex &index) const
   {
     MarkerBrowserTreeViewModelCacheEntry *node = (MarkerBrowserTreeViewModelCacheEntry *)(index.internalPointer ());
-    if (node) {
+    if (node && mp_database) {
 
       rdb::id_type id = node->id ();
       bool none = false;
@@ -638,6 +638,10 @@ public:
 
   QModelIndex next_index (QModelIndex current_index, bool up)
   {
+    if (!mp_database) {
+      return QModelIndex ();
+    }
+
     MarkerBrowserTreeViewModelCacheEntry *node = (MarkerBrowserTreeViewModelCacheEntry *) current_index.internalPointer ();
     
     rdb::id_type id = node->id ();
diff --git a/src/tl/unit_tests/tlThreadedWorkers.cc b/src/tl/unit_tests/tlThreadedWorkers.cc
index 877e81fa3..1dd1684cb 100644
--- a/src/tl/unit_tests/tlThreadedWorkers.cc
+++ b/src/tl/unit_tests/tlThreadedWorkers.cc
@@ -41,7 +41,7 @@ inline void usleep(long us)
 class Sum
 {
 public:
-  Sum () : m_sum(0) { }
+  Sum () : m_sum(0), m_flag (false) { }
 
   void reset () { lock.lock (); m_sum = 0; lock.unlock (); m_flag = false; }
   void add(int n) { lock.lock (); m_sum += n; lock.unlock (); m_flag = true; }