diff --git a/uppsrc/Core/BlockStream.cpp b/uppsrc/Core/BlockStream.cpp
index dc2ceb8df..2cbd28510 100644
--- a/uppsrc/Core/BlockStream.cpp
+++ b/uppsrc/Core/BlockStream.cpp
@@ -17,7 +17,7 @@ void BlockStream::SetBufferSize(dword size)
 	while(size >> (n + 1))
 		n++;
 	pagesize = 1 << n;
-	pagemask = (int64)-1 << n;
+	pagemask = (uint64)-1 << n;
 	if(buffer)
 		delete[] buffer;
 	buffer = new byte[pagesize];
diff --git a/uppsrc/Core/Defs.h b/uppsrc/Core/Defs.h
index 4ca3cfedb..73e0f361f 100644
--- a/uppsrc/Core/Defs.h
+++ b/uppsrc/Core/Defs.h
@@ -540,3 +540,11 @@ type& GLOBAL_VP_INIT(type, name, param)
 
 #define GLOBAL_V_INIT(type, name)   GLOBAL_VP_INIT(type, name, init_)
 #define GLOBAL_VAR_INIT(type, name) type& GLOBAL_V_INIT(type, name)
+
+#if __GNUC__ > 6
+	#define NOUBSAN __attribute__((no_sanitize_undefined))
+#elif __clang__ > 6
+	#define NOUBSAN __attribute__((no_sanitize("undefined")))
+#else
+	#define NOUBSAN
+#endif
diff --git a/uppsrc/Core/Hash.cpp b/uppsrc/Core/Hash.cpp
index 61bddfbab..a961f6bfb 100644
--- a/uppsrc/Core/Hash.cpp
+++ b/uppsrc/Core/Hash.cpp
@@ -295,8 +295,9 @@ void HashBase::Swap(HashBase& b) {
 }
 
 
-#ifdef CPU_X86
+#ifdef CPU_UNALIGNED
 
+NOUBSAN // CPU supports unaligned memory access
 unsigned memhash(const void *ptr, size_t count)
 {
 	unsigned hash = 1234567890U;
diff --git a/uppsrc/Core/InetUtil.cpp b/uppsrc/Core/InetUtil.cpp
index df9ab1c10..ab0b947fb 100644
--- a/uppsrc/Core/InetUtil.cpp
+++ b/uppsrc/Core/InetUtil.cpp
@@ -235,12 +235,14 @@ String QPDecode(const char *s, bool underscore_to_space)
 	return r;
 }
 
-String Base64Encode(const char *b, const char *e)
+String Base64Encode(const char *_b, const char *_e)
 {
 	static const char encoder[] =
 		"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 		"abcdefghijklmnopqrstuvwxyz"
 		"0123456789+/";
+	const byte *b = (byte *)_b; // avoid left shift of negative value sanitizer issue
+	const byte *e = (byte *)_e;
 	if(b == e)
 		return Null;
 	int out = (int(e - b) + 2) / 3 * 4;
diff --git a/uppsrc/Core/Ops.h b/uppsrc/Core/Ops.h
index c955095c8..d56453c7b 100644
--- a/uppsrc/Core/Ops.h
+++ b/uppsrc/Core/Ops.h
@@ -1,11 +1,11 @@
 #if defined(CPU_UNALIGNED) && defined(CPU_LE) || __ARM_ARCH_7A__
-inline int    Peek16le(const void *ptr)  { return *(const word *)ptr; }
-inline int    Peek32le(const void *ptr)  { return *(const dword *)ptr; }
-inline int64  Peek64le(const void *ptr)  { return *(const int64 *)ptr; }
+NOUBSAN inline int    Peek16le(const void *ptr)  { return *(const word *)ptr; }
+NOUBSAN inline int    Peek32le(const void *ptr)  { return *(const dword *)ptr; }
+NOUBSAN inline int64  Peek64le(const void *ptr)  { return *(const int64 *)ptr; }
 
-inline void   Poke16le(const void *ptr, int val)    { *(word *)ptr = val; }
-inline void   Poke32le(const void *ptr, int val)    { *(dword *)ptr = val; }
-inline void   Poke64le(const void *ptr, int64 val)  { *(int64 *)ptr = val; }
+NOUBSAN inline void   Poke16le(const void *ptr, int val)    { *(word *)ptr = val; }
+NOUBSAN inline void   Poke32le(const void *ptr, int val)    { *(dword *)ptr = val; }
+NOUBSAN inline void   Poke64le(const void *ptr, int64 val)  { *(int64 *)ptr = val; }
 #else
 inline int    Peek16le(const void *ptr)  { return MAKEWORD(((byte *)ptr)[0], ((byte *)ptr)[1]); }
 inline int    Peek32le(const void *ptr)  { return MAKELONG(Peek16le(ptr), Peek16le((byte *)ptr + 2)); }
diff --git a/uppsrc/Core/Other.h b/uppsrc/Core/Other.h
index fd60b1c38..a966f2294 100644
--- a/uppsrc/Core/Other.h
+++ b/uppsrc/Core/Other.h
@@ -284,20 +284,20 @@ protected:
 	void LPN(int i)                      { link_prev[i]->link_next[i] = link_next[i]->link_prev[i] = (T *)this; }
 
 public:
-	T       *GetPtr()                    { return (T *) this; }
+	NOUBSAN	T *GetPtr()                  { return (T *) this; }
 	const T *GetPtr() const              { return (const T *) this; }
 	T       *GetNext(int i = 0)          { return link_next[i]; }
 	T       *GetPrev(int i = 0)          { return link_prev[i]; }
 	const T *GetNext(int i = 0) const    { return link_next[i]; }
 	const T *GetPrev(int i = 0) const    { return link_prev[i]; }
 
-	void LinkSelf(int i = 0)             { link_next[i] = link_prev[i] = (T *)this; }
+	NOUBSAN	void LinkSelf(int i = 0)             { link_next[i] = link_prev[i] = (T *)this; }
 	void LinkSelfAll()                   { for(int i = 0; i < N; i++) LinkSelf(i); }
 	void Unlink(int i = 0)               { link_next[i]->link_prev[i] = link_prev[i]; link_prev[i]->link_next[i] = link_next[i];
 	                                       LinkSelf(i); }
 	void UnlinkAll()                     { for(int i = 0; i < N; i++) Unlink(i); }
-	void LinkBefore(Link *n, int i = 0)  { link_next[i] = (T *)n; link_prev[i] = link_next[i]->link_prev[i]; LPN(i); }
-	void LinkAfter(Link *p, int i = 0)   { link_prev[i] = (T *)p; link_next[i] = link_prev[i]->link_next[i]; LPN(i); }
+	NOUBSAN	void LinkBefore(Link *n, int i = 0)  { link_next[i] = (T *)n; link_prev[i] = link_next[i]->link_prev[i]; LPN(i); }
+	NOUBSAN	void LinkAfter(Link *p, int i = 0)   { link_prev[i] = (T *)p; link_next[i] = link_prev[i]->link_next[i]; LPN(i); }
 
 	T   *InsertNext(int i = 0)           { T *x = new T; x->LinkAfter(this, i); return x; }
 	T   *InsertPrev(int i = 0)           { T *x = new T; x->LinkBefore(this, i); return x; }
diff --git a/uppsrc/Core/Stream.h b/uppsrc/Core/Stream.h
index 81c706829..4ba821ba3 100644
--- a/uppsrc/Core/Stream.h
+++ b/uppsrc/Core/Stream.h
@@ -91,7 +91,7 @@ public:
 	byte       *PutPtr(int size = 1) { ASSERT(size > 0); if(ptr + size <= wrlim) { byte *p = ptr; ptr += size; return p; }; return NULL; }
 	const byte *GetSzPtr(int& size)  { Term(); size = int(rdlim - ptr); byte *p = ptr; ptr += size; return p; }
 
-	void      Put(const void *data, int size)  { ASSERT(size >= 0); if(ptr + size <= wrlim) { memcpy(ptr, data, size); ptr += size; } else _Put(data, size); }
+	void      Put(const void *data, int size)  { ASSERT(size >= 0); if(size) if(ptr + size <= wrlim) { memcpy(ptr, data, size); ptr += size; } else _Put(data, size); }
 	int       Get(void *data, int size)        { ASSERT(size >= 0); if(ptr + size <= rdlim) { memcpy(data, ptr, size); ptr += size; return size; } return _Get(data, size); }
 
 	void      Put(const String& s)   { Put((const char *) s, s.GetLength()); }
@@ -113,10 +113,10 @@ public:
 	bool      GetAll(Huge& h, size_t size);
 
 	int       Get8()                 { return ptr < rdlim ? *ptr++ : _Get8(); }
-#ifdef CPU_X86
-	int       Get16()                { if(ptr + 1 >= rdlim) return _Get16(); int q = *(word *)ptr; ptr += 2; return q; }
-	int       Get32()                { if(ptr + 3 >= rdlim) return _Get32(); int q = *(dword *)ptr; ptr += 4; return q; }
-	int64     Get64()                { if(ptr + 7 >= rdlim) return _Get64(); int64 q = *(int64 *)ptr; ptr += 8; return q; }
+#if defined(CPU_UNALIGNED) && defined(CPU_LE)
+	NOUBSAN	int   Get16()            { if(ptr + 1 >= rdlim) return _Get16(); int q = *(word *)ptr; ptr += 2; return q; }
+	NOUBSAN	int   Get32()            { if(ptr + 3 >= rdlim) return _Get32(); int q = *(dword *)ptr; ptr += 4; return q; }
+	NOUBSAN	int64 Get64()            { if(ptr + 7 >= rdlim) return _Get64(); int64 q = *(int64 *)ptr; ptr += 8; return q; }
 #else
 	int       Get16()                { return _Get16(); }
 	int       Get32()                { return _Get32(); }
@@ -143,10 +143,10 @@ public:
 
 	String    GetLine();
 
-#ifdef CPU_X86
-	void      Put16(word q)          { if(ptr + 1 < wrlim) { *(word *)ptr = q; ptr += 2; } else Put(&q, 2); }
-	void      Put32(dword q)         { if(ptr + 3 < wrlim) { *(dword *)ptr = q; ptr += 4; } else Put(&q, 4); }
-	void      Put64(int64 q)         { if(ptr + 7 < wrlim) { *(int64 *)ptr = q; ptr += 8; } else Put(&q, 8); }
+#if defined(CPU_UNALIGNED) && defined(CPU_LE)
+	NOUBSAN void Put16(word q)       { if(ptr + 1 < wrlim) { *(word *)ptr = q; ptr += 2; } else Put(&q, 2); }
+	NOUBSAN void Put32(dword q)      { if(ptr + 3 < wrlim) { *(dword *)ptr = q; ptr += 4; } else Put(&q, 4); }
+	NOUBSAN void Put64(int64 q)      { if(ptr + 7 < wrlim) { *(int64 *)ptr = q; ptr += 8; } else Put(&q, 8); }
 #else
 	void      Put16(word q)          { Put(&q, 2); }
 	void      Put32(dword q)         { Put(&q, 4); }
diff --git a/uppsrc/Core/lheap.cpp b/uppsrc/Core/lheap.cpp
index 1cbb2a526..0f431536a 100644
--- a/uppsrc/Core/lheap.cpp
+++ b/uppsrc/Core/lheap.cpp
@@ -43,7 +43,7 @@ void Heap::GlobalLInit()
 		}
 		k = LBINS - 1;
 		for(int i = MAXBLOCK / 8; i >= 0; i--) {
-			while(i * 8 < BinSz[k] && k >= 0) k--;
+			while(k >= 0 && i * 8 < BinSz[k]) k--;
 			BlBin[i] = k;
 		}
 		BlBin[0] = 0;
diff --git a/uppsrc/CppBase/CppBase.h b/uppsrc/CppBase/CppBase.h
index 461664ec6..ffc6f312b 100644
--- a/uppsrc/CppBase/CppBase.h
+++ b/uppsrc/CppBase/CppBase.h
@@ -448,29 +448,27 @@ struct Parser {
 	};
 
 	struct Decla {
-		bool    s_static;
-		bool    s_extern;
-		bool    s_register;
-		bool    s_mutable;
-		bool    s_explicit;
-		bool    s_virtual;
+		bool    s_static = false;
+		bool    s_extern = false;
+		bool    s_register = false;
+		bool    s_mutable = false;
+		bool    s_explicit = false;
+		bool    s_virtual = false;
 		String  name;
-		bool    function;
-		bool    type_def;
-		bool    isfriend;
-		bool    istemplate;
-		bool    istructor;
-		bool    isdestructor;
-		bool    isptr;
-		bool    nofn;
-		bool    oper;
-		bool    castoper;
+		bool    function = false;
+		bool    type_def = false;
+		bool    isfriend = false;
+		bool    istemplate = false;
+		bool    istructor = false;
+		bool    isdestructor = false;
+		bool    isptr = false;
+		bool    nofn = false;
+		bool    oper = false;
+		bool    castoper = false;
 
 		String  tnames;
 		String  type;
 		String  natural;
-
-		Decla();
 	};
 
 	struct Decl : Decla {
diff --git a/uppsrc/CppBase/Parser.cpp b/uppsrc/CppBase/Parser.cpp
index f2fee3c0b..b7e5666a2 100644
--- a/uppsrc/CppBase/Parser.cpp
+++ b/uppsrc/CppBase/Parser.cpp
@@ -352,15 +352,6 @@ bool Parser::IsNamespace(const String& scope)
 	return memcmp(~context.ns, ~scope, l) == 0 && findarg(context.ns[l], '\0', ':') >= 0;
 }
 
-Parser::Decla::Decla()
-{
-	function = type_def = false;
-	s_static = s_register = s_extern = s_mutable = s_explicit = s_virtual = false;
-	isfriend = istemplate = istructor = isptr = nofn = false;
-	castoper = oper = false;
-}
-
-
 bool Parser::Key(int code)
 {
 	if(lex == code) {
diff --git a/uppsrc/CtrlLib/ChGtk0.cpp b/uppsrc/CtrlLib/ChGtk0.cpp
index 0e2d9cf58..01ccaf625 100644
--- a/uppsrc/CtrlLib/ChGtk0.cpp
+++ b/uppsrc/CtrlLib/ChGtk0.cpp
@@ -473,6 +473,7 @@ void GtkIml(int uii, GtkWidget *w, int shadow, const char *detail, int type, int
 	GtkIml(uii + 3, w, shadow, 4, detail, type, cx, cy, rect, maxcx, maxcy);
 }
 
+NOUBSAN // we are treating fg and following GdkColor arrays as single array
 Color ChGtkColor(int ii, GtkWidget *widget)
 {
 	GdkColor cc = ((GtkStyle *)gtk_widget_get_style(widget))->fg[ii];
diff --git a/uppsrc/Draw/Uhd.cpp b/uppsrc/Draw/Uhd.cpp
index 665f934ce..73d503062 100644
--- a/uppsrc/Draw/Uhd.cpp
+++ b/uppsrc/Draw/Uhd.cpp
@@ -85,10 +85,10 @@ Image Upscale2x(const Image& src)
 		struct SFilter : ImageFilter9 { // Improve contours
 			virtual RGBA operator()(const RGBA **mx) {
 				RGBA s = mx[1][1];
-				int l = mx[0][1].a;
-				int r = mx[2][1].a;
-				int t = mx[1][0].a;
-				int b = mx[1][2].a;
+				dword l = mx[0][1].a;
+				dword r = mx[2][1].a;
+				dword t = mx[1][0].a;
+				dword b = mx[1][2].a;
 				int l1 = 110;
 				int l2 = 230;
 				return l * r * t * b != 0 || s.a > l1 || mx[0][1].a > l2 || mx[2][1].a > l2 || mx[1][0].a > l2 || mx[1][2].a > l2 ? s
diff --git a/uppsrc/IconDes/IconDes.h b/uppsrc/IconDes/IconDes.h
index ae68348a4..010abb23f 100644
--- a/uppsrc/IconDes/IconDes.h
+++ b/uppsrc/IconDes/IconDes.h
@@ -168,10 +168,10 @@ private:
 	Point        startpoint;
 	Rect         m1refresh;
 	void        (IconDes::*tool)(Point p, dword flags);
-	bool         doselection;
-	bool         selectrect;
+	bool         doselection = false;
+	bool         selectrect = false;
 	int          paste_mode;
-	bool         show_small;
+	bool         show_small = false;
 
 	ScrollBars   sb;
 	Scroller     scroller;
diff --git a/uppsrc/IconDes/ImageOp.cpp b/uppsrc/IconDes/ImageOp.cpp
index d29a6b59c..93380f2bf 100644
--- a/uppsrc/IconDes/ImageOp.cpp
+++ b/uppsrc/IconDes/ImageOp.cpp
@@ -160,7 +160,7 @@ String PackImlData(const Vector<ImageIml>& image)
 	for(const ImageIml& m : image) {
 		const Image& img = m.image;
 		StringStream ss;
-		ss.Put((img.GetResolution() << 6) | m.flags);
+		ss.Put(((dword)img.GetResolution() << 6) | m.flags);
 		Size sz = img.GetSize();
 		ss.Put16le(sz.cx);
 		ss.Put16le(sz.cy);
diff --git a/uppsrc/RichEdit/Editor.cpp b/uppsrc/RichEdit/Editor.cpp
index f6aaad8c0..e226c9170 100644
--- a/uppsrc/RichEdit/Editor.cpp
+++ b/uppsrc/RichEdit/Editor.cpp
@@ -69,7 +69,7 @@ Zoom RichEdit::GetZoom() const
 
 Size RichEdit::GetZoomedPage() const
 {
-	return Size(GetTextRect().Width(), pagesz.cy == INT_MAX ? INT_MAX : GetZoom() * pagesz.cy);
+	return Size(GetTextRect().Width(), pagesz.cy == INT_MAX ? INT_MAX / 2 : GetZoom() * pagesz.cy);
 }
 
 int  RichEdit::GetPosY(PageY py) const
diff --git a/uppsrc/RichText/Table.h b/uppsrc/RichText/Table.h
index 3a87f0a78..2b22352ec 100644
--- a/uppsrc/RichText/Table.h
+++ b/uppsrc/RichText/Table.h
@@ -117,7 +117,7 @@ private:
 	};
 
 	struct TabLayout : Layout {
-		bool              hasheader;
+		bool              hasheader = false;
 		Layout            header;
 		Size              sz;
 		PageY             py;
diff --git a/uppsrc/RichText/Text.h b/uppsrc/RichText/Text.h
index 2f54e18de..27d00bb0d 100644
--- a/uppsrc/RichText/Text.h
+++ b/uppsrc/RichText/Text.h
@@ -2,7 +2,7 @@ class RichText : public RichTxt, public DeepCopyOption<RichText> {
 	mutable Mutex mutex; // To cover all those laze evaluation scenarios
 	RichStyles    style;
 	String        footer_hack; // ugly hack
-	bool          nolinks; // another ugly hack
+	bool          nolinks = false; // another ugly hack
 
 	void       Init();
 
diff --git a/uppsrc/RichText/Txt.h b/uppsrc/RichText/Txt.h
index 2daa348c6..190268e91 100644
--- a/uppsrc/RichText/Txt.h
+++ b/uppsrc/RichText/Txt.h
@@ -114,9 +114,9 @@ protected:
 	int  r_parti;
 	int  r_paraocx;
 	int  r_paraocy;
-	bool r_keep;
-	bool r_keepnext;
-	bool r_newpage;
+	bool r_keep = false;
+	bool r_keepnext = false;
+	bool r_newpage = false;
 
 	void       Init();