diff --git a/make/linux/makefiles/gcc.make b/make/linux/makefiles/gcc.make
index a158786a8916b44467e4a2ba9a579a96d326db9d..0d56be485281c800ca2e674d5bca8e20c3d0de7b 100644
--- a/make/linux/makefiles/gcc.make
+++ b/make/linux/makefiles/gcc.make
@@ -84,8 +84,17 @@ endif
 
 # Compiler warnings are treated as errors
 WARNINGS_ARE_ERRORS = -Werror
+
 # Except for a few acceptable ones
+# Since GCC 4.3, -Wconversion has changed its meanings to warn these implicit
+# conversions which might affect the values. To avoid that, we need to turn
+# it off explicitly. 
+ifneq "$(shell expr \( $(CC_VER_MAJOR) \> 4 \) \| \( \( $(CC_VER_MAJOR) = 4 \) \& \( $(CC_VER_MINOR) \>= 3 \) \))" "0"
+ACCEPTABLE_WARNINGS = -Wpointer-arith -Wsign-compare
+else
 ACCEPTABLE_WARNINGS = -Wpointer-arith -Wconversion -Wsign-compare
+endif
+
 CFLAGS_WARN/DEFAULT = $(WARNINGS_ARE_ERRORS) $(ACCEPTABLE_WARNINGS)
 # Special cases
 CFLAGS_WARN/BYFILE = $(CFLAGS_WARN/$@)$(CFLAGS_WARN/DEFAULT$(CFLAGS_WARN/$@)) 
diff --git a/src/share/vm/adlc/adlc.hpp b/src/share/vm/adlc/adlc.hpp
index fc81ee00a5ed83ca6217d382569ee67194ddd528..14bc5d6b7388d0fd1e83d23063a714300d15860b 100644
--- a/src/share/vm/adlc/adlc.hpp
+++ b/src/share/vm/adlc/adlc.hpp
@@ -29,11 +29,7 @@
 // standard library constants
 #include "stdio.h"
 #include "stdlib.h"
-#if _MSC_VER >= 1300  // Visual C++ 7.0 or later
 #include <iostream>
-#else
-#include <iostream.h>
-#endif
 #include "string.h"
 #include "ctype.h"
 #include "stdarg.h"
diff --git a/src/share/vm/adlc/filebuff.hpp b/src/share/vm/adlc/filebuff.hpp
index fa84e09bd2a8267d2ca6820cfee1754897eca478..fdfa985db4c9995f2c5b6e5c58dcd44d5aec19f0 100644
--- a/src/share/vm/adlc/filebuff.hpp
+++ b/src/share/vm/adlc/filebuff.hpp
@@ -23,13 +23,9 @@
  */
 
 // FILEBUFF.HPP - Definitions for parser file buffering routines
-
-#if _MSC_VER >= 1300  // Visual C++ 7.0 or later
 #include <iostream>
-#else
-#include <iostream.h>
-#endif
 
+using namespace std;
 // STRUCTURE FOR HANDLING INPUT AND OUTPUT FILES
 typedef struct {
   const char *_name;