--- a/CommonSource/ExternalReadFormats/BamWriter.cpp
+++ b/CommonSource/ExternalReadFormats/BamWriter.cpp
@@ -496,7 +496,7 @@
 	buffer[6] = 0xffffffff;  // mate_pos
 	buffer[7] = 0;           // ins_size
 
-	const char* startChar = '\0';
+	const char* startChar = NULL;
 	
 	// write the block size
 	const unsigned int dataBlockSize = nameLen + packedCigarLen + encodedQueryLen + queryLen;
@@ -652,7 +652,7 @@
 	unsigned int zaTagLen = 0;
 	string zaTag;
 	char* pZaTag;
-	if ((zaString != 0) && (zaString != (char)0)) {
+	if ((zaString != 0) && (zaString[0] != '\0')) {
 		zaTagLen = 3 + strlen( zaString ) + 1;
 		zaTag.resize( zaTagLen );
 		pZaTag = (char*)zaTag.data();
@@ -776,7 +776,7 @@
 	BgzfWrite(mdTag.data(), mdTagLen);
 
 	// write the ZA tag
-	if ( zaString != 0 && (zaString != (char)0))
+	if ( zaString != 0 && (zaString[0] != '\0'))
 		BgzfWrite(zaTag.data(), zaTagLen);
 	
 	// write the ZN tag
--- a/MosaikAligner/AlignmentThread.cpp
+++ b/MosaikAligner/AlignmentThread.cpp
@@ -591,7 +591,7 @@
 	buffer.al              = al;
 	buffer.noCigarMdNm     = noCigarMdNm;
 	buffer.notShowRnamePos = notShowRnamePos;
-	if ( zaString == (char)0 ) 
+	if ( zaString == NULL ) 
 		buffer.zaString.clear();
 	else
 		buffer.zaString = zaString;