diff --git a/qa/qa_utils/mocks.cpp b/qa/qa_utils/mocks.cpp
index 676265b4c8..e2360b2b75 100644
--- a/qa/qa_utils/mocks.cpp
+++ b/qa/qa_utils/mocks.cpp
@@ -176,21 +176,26 @@ void DIALOG_FIND::onClose( wxCommandEvent& aEvent )
 }
 
 
-DIALOG_FIND_BASE::DIALOG_FIND_BASE( wxWindow* parent,
-        wxWindowID id,
-        const wxString& title,
-        const wxPoint& pos,
-        const wxSize& size,
-        long style ) : DIALOG_SHIM( parent, id, title, pos, size, style )
+DIALOG_FIND_BASE::DIALOG_FIND_BASE( wxWindow* parent, wxWindowID id, const wxString& title,
+                                    const wxPoint& pos, const wxSize& size, long style ) :
+        DIALOG_SHIM( parent, id, title, pos, size, style )
 {
     // these members are initialized only to avoid warnings about non initialized vars
-    /*
-    m_staticText1 = nullptr;
-    m_SearchCombo = nullptr;
-    m_button1 = nullptr;
-    m_button2 = nullptr;
-    m_button3 = nullptr;
-    */
+    searchStringLabel = nullptr;
+    m_searchCombo = nullptr;
+    m_matchCase = nullptr;
+    m_matchWords = nullptr;
+    m_wildcards = nullptr;
+    m_wrap = nullptr;
+    m_includeValues = nullptr;
+    m_includeReferences = nullptr;
+    m_includeTexts = nullptr;
+    m_includeMarkers = nullptr;
+    m_includeVias = nullptr;
+    m_findNext = nullptr;
+    m_findPrevious = nullptr;
+    m_searchAgain = nullptr;
+    m_closeButton = nullptr;
 }
 
 
diff --git a/thirdparty/potrace/include/bitmap.h b/thirdparty/potrace/include/bitmap.h
index bc5f945c5b..e1765e08a9 100644
--- a/thirdparty/potrace/include/bitmap.h
+++ b/thirdparty/potrace/include/bitmap.h
@@ -161,7 +161,8 @@ static inline void bm_clear( potrace_bitmap_t* bm, int c )
      *  guaranteed that size will fit into the ptrdiff_t type. */
     ptrdiff_t size = bm_size( bm );
 
-    memset( bm_base( bm ), c ? -1 : 0, size );
+    if( size > 0 )
+        memset( bm_base( bm ), c ? -1 : 0, size );
 }
 
 
diff --git a/thirdparty/potrace/src/greymap.cpp b/thirdparty/potrace/src/greymap.cpp
index 88e7641f42..8e7f812fd4 100644
--- a/thirdparty/potrace/src/greymap.cpp
+++ b/thirdparty/potrace/src/greymap.cpp
@@ -159,7 +159,8 @@ void gm_clear( greymap_t* gm, int b )
 
     if( b == 0 )
     {
-        memset( gm->base, 0, size );
+        if( size > 0 )
+            memset( gm->base, 0, size );
     }
     else
     {
@@ -176,7 +177,7 @@ void gm_clear( greymap_t* gm, int b )
 
 /* turn the given greymap upside down. This does not move the pixel
  *  data or change the base address. */
-static inline void gm_flip( greymap_t* gm )
+static inline void GM_FLIP( greymap_t* gm )
 {
     int dy = gm->dy;