diff --git a/source/Disk.cpp b/source/Disk.cpp
index c286bfe3..05761012 100644
--- a/source/Disk.cpp
+++ b/source/Disk.cpp
@@ -1336,11 +1336,12 @@ static void DiskLoadSnapshotDriveUnit(YamlLoadHelper& yamlLoadHelper, UINT unit)
 	g_aFloppyDisk[unit].trackimagedata	= yamlLoadHelper.LoadUint(SS_YAML_KEY_TRACK_IMAGE_DATA);
 	g_aFloppyDisk[unit].trackimagedirty	= yamlLoadHelper.LoadUint(SS_YAML_KEY_TRACK_IMAGE_DIRTY);
 
-	std::auto_ptr<BYTE> pTrack( new BYTE [NIBBLES_PER_TRACK] );
-	memset(pTrack.get(), 0, NIBBLES_PER_TRACK);
+	std::vector<BYTE> track;
+	track.resize(NIBBLES_PER_TRACK);
+	memset(&track[0], 0, track.size());
 	if (yamlLoadHelper.GetSubMap(SS_YAML_KEY_TRACK_IMAGE))
 	{
-		yamlLoadHelper.LoadMemory(pTrack.get(), NIBBLES_PER_TRACK);
+		yamlLoadHelper.LoadMemory(&track[0], NIBBLES_PER_TRACK);
 		yamlLoadHelper.PopMap();
 	}
 
@@ -1356,7 +1357,7 @@ static void DiskLoadSnapshotDriveUnit(YamlLoadHelper& yamlLoadHelper, UINT unit)
 		if (g_aFloppyDisk[unit].trackimage == NULL)
 			bImageError = true;
 		else
-			memcpy(g_aFloppyDisk[unit].trackimage, pTrack.get(), NIBBLES_PER_TRACK);
+			memcpy(g_aFloppyDisk[unit].trackimage, &track[0], NIBBLES_PER_TRACK);
 	}
 
 	if (bImageError)
diff --git a/source/DiskImageHelper.cpp b/source/DiskImageHelper.cpp
index d631c597..a2b21ec8 100644
--- a/source/DiskImageHelper.cpp
+++ b/source/DiskImageHelper.cpp
@@ -192,9 +192,6 @@ bool CImageBase::WriteBlock(ImageInfo* pImageInfo, const int nBlock, LPBYTE pBlo
 			// Horribly inefficient! (Unzip to a normal file if you want better performance!)
 			const UINT uNewImageSize = Offset+HD_BLOCK_SIZE;
 			BYTE* pNewImageBuffer = new BYTE [uNewImageSize];
-			_ASSERT(pNewImageBuffer);
-			if (!pNewImageBuffer)
-				return false;
 
 			memcpy(pNewImageBuffer, pImageInfo->pImageBuffer, pImageInfo->uImageSize);
 			memset(&pNewImageBuffer[pImageInfo->uImageSize], 0, uNewImageSize-pImageInfo->uImageSize);	// Should always be HD_BLOCK_SIZE (so this is redundant)
@@ -1153,8 +1150,6 @@ ImageError_e CImageHelperBase::CheckGZipFile(LPCTSTR pszImageFilename, ImageInfo
 
 	const UINT MAX_UNCOMPRESSED_SIZE = GetMaxImageSize() + 1;	// +1 to detect images that are too big
 	pImageInfo->pImageBuffer = new BYTE[MAX_UNCOMPRESSED_SIZE];
-	if (!pImageInfo->pImageBuffer)
-		return eIMAGE_ERROR_BAD_POINTER;
 
 	int nLen = gzread(hGZFile, pImageInfo->pImageBuffer, MAX_UNCOMPRESSED_SIZE);
 	if (nLen < 0 || nLen == MAX_UNCOMPRESSED_SIZE)
@@ -1222,8 +1217,6 @@ ImageError_e CImageHelperBase::CheckZipFile(LPCTSTR pszImageFilename, ImageInfo*
 		return eIMAGE_ERROR_BAD_SIZE;
 
 	pImageInfo->pImageBuffer = new BYTE[uFileSize];
-	if (!pImageInfo->pImageBuffer)
-		return eIMAGE_ERROR_BAD_POINTER;
 
 	nRes = unzOpenCurrentFile(hZipFile);
 	if (nRes != UNZ_OK)
@@ -1352,8 +1345,6 @@ ImageError_e CImageHelperBase::CheckNormalFile(LPCTSTR pszImageFilename, ImageIn
 		const UINT uDetectSize = GetMinDetectSize(dwSize, &bTempDetectBuffer);
 
 		pImageInfo->pImageBuffer = new BYTE [dwSize];
-		if (!pImageInfo->pImageBuffer)
-			return eIMAGE_ERROR_BAD_POINTER;
 
 		DWORD dwBytesRead;
 		BOOL bRes = ReadFile(hFile, pImageInfo->pImageBuffer, dwSize, &dwBytesRead, NULL);
@@ -1377,9 +1368,6 @@ ImageError_e CImageHelperBase::CheckNormalFile(LPCTSTR pszImageFilename, ImageIn
 		if (pImageType && dwSize)
 		{
 			pImageInfo->pImageBuffer = new BYTE [dwSize];
-			if (!pImageInfo->pImageBuffer)
-				return eIMAGE_ERROR_BAD_POINTER;
-
 			ZeroMemory(pImageInfo->pImageBuffer, dwSize);
 		}
 	}
diff --git a/source/Speaker.cpp b/source/Speaker.cpp
index ff58a7fd..328093a9 100644
--- a/source/Speaker.cpp
+++ b/source/Speaker.cpp
@@ -130,7 +130,7 @@ static void InitRemainderBuffer()
 	SetClksPerSpkrSample();
 
 	g_nRemainderBufferSize = (UINT) g_fClksPerSpkrSample;
-	if ((double)g_nRemainderBufferSize != g_fClksPerSpkrSample)
+	if ((double)g_nRemainderBufferSize < g_fClksPerSpkrSample)
 		g_nRemainderBufferSize++;
 
 	g_pRemainderBuffer = new short [g_nRemainderBufferSize];
@@ -339,10 +339,10 @@ BYTE __stdcall SpkrToggle (WORD, WORD, BYTE, BYTE, ULONG nCyclesLeft)
       if (g_bQuieterSpeaker)
       {
        // quieten the speaker if 8 bit DAC in use
-       if (g_nSpeakerData == (SPKR_DATA_INIT >> 2))
+       if (g_nSpeakerData == (SPKR_DATA_INIT/4))	// NB. Don't shift -ve number right: undefined behaviour (MSDN says: implementation-dependent)
         g_nSpeakerData = ~g_nSpeakerData;
        else
-        g_nSpeakerData = SPKR_DATA_INIT>>2;
+        g_nSpeakerData = SPKR_DATA_INIT/4;	// NB. Don't shift -ve number right: undefined behaviour (MSDN says: implementation-dependent)
       }
       else
       {
diff --git a/source/Tfe/Uilib.cpp b/source/Tfe/Uilib.cpp
index 262c5883..b350b8ce 100644
--- a/source/Tfe/Uilib.cpp
+++ b/source/Tfe/Uilib.cpp
@@ -58,6 +58,12 @@ void uilib_get_general_window_extents(HWND hwnd, int *xsize, int *ysize)
     strlen = SendMessage(hwnd, WM_GETTEXTLENGTH, 0, 0);
 	/* RGJ added cast for AppleWin */
     buffer = (char *) malloc(strlen + 1);
+	if (buffer == NULL)	// TC: add null check for AppleWin
+	{
+		*xsize = 0;
+		*ysize = 0;
+		return;
+	}
     GetWindowText(hwnd, buffer, strlen + 1);
 
     hdc = GetDC(hwnd);
diff --git a/source/Tfe/Uilib.h b/source/Tfe/Uilib.h
index f8ec8c8e..22865eab 100644
--- a/source/Tfe/Uilib.h
+++ b/source/Tfe/Uilib.h
@@ -32,8 +32,6 @@
 #include <windows.h>
 #include <tchar.h>
 
-extern void uilib_get_general_window_extents(HWND hwnd, int *xsize, int *ysize);
-
 typedef struct {
     unsigned int idc;
     int element_type;