--- a/configure.in
+++ b/configure.in
@@ -1739,47 +1739,54 @@ ia64*-hpux*)
         MKSHLIB_FORCE_ALL=
         MKSHLIB_UNFORCE_ALL=
         DSO_LDOPTS=-SUBSYSTEM:WINDOWS
         _USE_CPP_INCLUDE_FLAG=1
         _DEFINES_CFLAGS='-FI $(DEPTH)/comm-config.h -DMOZILLA_CLIENT'
         _DEFINES_CXXFLAGS='-FI $(DEPTH)/comm-config.h -DMOZILLA_CLIENT'
         CFLAGS="$CFLAGS -W3 -Gy -Fd\$(COMPILE_PDBFILE)"
         CXXFLAGS="$CXXFLAGS -W3 -Gy -Fd\$(COMPILE_PDBFILE)"
-        CXXFLAGS="$CXXFLAGS -wd4800" # disable warning "forcing value to bool"
+        # MSVC warning C4345 warns of newly conformant behavior as of VS2003.
+        # MSVC warning C4351 warns of newly conformant behavior as of VS2005.
+        # MSVC warning C4800 warns when a value is implicitly cast to bool,
+        # because this also forces narrowing to a single byte, which can be a
+        # perf hit.  But this matters so little in practice (and often we want
+        # that behavior) that it's better to turn it off.
+        CXXFLAGS="$CXXFLAGS -wd4345 -wd4351 -wd4800"
+        # make 'foo == bar;' error out
+        CFLAGS="$CFLAGS -we4553"
+        CXXFLAGS="$CXXFLAGS -we4553"
         LIBS="$LIBS kernel32.lib user32.lib gdi32.lib winmm.lib wsock32.lib advapi32.lib"
         MOZ_DEBUG_FLAGS='-Zi'
         MOZ_DEBUG_LDFLAGS='-DEBUG -DEBUGTYPE:CV'
         WARNINGS_AS_ERRORS='-WX'
         MOZ_OPTIMIZE_FLAGS='-O1'
         MOZ_JS_STATIC_LIBS='$(LIBXUL_DIST)/lib/js_static.lib'
         MOZ_JS_SHARED_LIBS='$(LIBXUL_DIST)/lib/mozjs.lib'
         MOZ_FIX_LINK_PATHS=
         DYNAMIC_XPCOM_LIBS='$(LIBXUL_DIST)/lib/xpcom.lib $(LIBXUL_DIST)/lib/xpcom_core.lib $(LIBXUL_DIST)/lib/mozalloc.lib'
         XPCOM_FROZEN_LDOPTS='$(LIBXUL_DIST)/lib/xpcom.lib $(LIBXUL_DIST)/lib/mozalloc.lib'
         LIBXUL_LIBS='$(LIBXUL_DIST)/lib/xpcom.lib $(LIBXUL_DIST)/lib/xul.lib $(LIBXUL_DIST)/lib/mozalloc.lib'
         MOZ_COMPONENT_NSPR_LIBS='$(NSPR_LIBS)'
-        if test $_MSC_VER -ge 1400; then
-            LDFLAGS="$LDFLAGS -LARGEADDRESSAWARE -NXCOMPAT"
-            dnl For profile-guided optimization
-            PROFILE_GEN_CFLAGS="-GL"
-            PROFILE_GEN_LDFLAGS="-LTCG:PGINSTRUMENT"
-            dnl XXX: PGO builds can fail with warnings treated as errors,
-            dnl specifically "no profile data available" appears to be
-            dnl treated as an error sometimes. This might be a consequence
-            dnl of using WARNINGS_AS_ERRORS in some modules, combined
-            dnl with the linker doing most of the work in the whole-program
-            dnl optimization/PGO case. I think it's probably a compiler bug,
-            dnl but we work around it here.
-            PROFILE_USE_CFLAGS="-GL -wd4624 -wd4952"
-            dnl XXX: should be -LTCG:PGOPTIMIZE, but that fails on libxul.
-            dnl Probably also a compiler bug, but what can you do?
-            PROFILE_USE_LDFLAGS="-LTCG:PGUPDATE"
-            LDFLAGS="$LDFLAGS -DYNAMICBASE"
-        fi
+        LDFLAGS="$LDFLAGS -LARGEADDRESSAWARE -NXCOMPAT"
+        dnl For profile-guided optimization
+        PROFILE_GEN_CFLAGS="-GL"
+        PROFILE_GEN_LDFLAGS="-LTCG:PGINSTRUMENT"
+        dnl XXX: PGO builds can fail with warnings treated as errors,
+        dnl specifically "no profile data available" appears to be
+        dnl treated as an error sometimes. This might be a consequence
+        dnl of using WARNINGS_AS_ERRORS in some modules, combined
+        dnl with the linker doing most of the work in the whole-program
+        dnl optimization/PGO case. I think it's probably a compiler bug,
+        dnl but we work around it here.
+        PROFILE_USE_CFLAGS="-GL -wd4624 -wd4952"
+        dnl XXX: should be -LTCG:PGOPTIMIZE, but that fails on libxul.
+        dnl Probably also a compiler bug, but what can you do?
+        PROFILE_USE_LDFLAGS="-LTCG:PGUPDATE"
+        LDFLAGS="$LDFLAGS -DYNAMICBASE"
     fi
     MOZ_JPEG_LIBS='$(call EXPAND_LIBNAME_PATH,jpeg32$(VERSION_NUMBER),$(DEPTH)/mozilla/jpeg)'
     MOZ_PNG_LIBS='$(call EXPAND_LIBNAME_PATH,png,$(DEPTH)/mozilla/modules/libimg/png)'
     AC_DEFINE(HAVE_SNPRINTF)
     AC_DEFINE(_WINDOWS)
     AC_DEFINE(WIN32)
     AC_DEFINE(XP_WIN)
     AC_DEFINE(XP_WIN32)
@@ -1831,26 +1838,23 @@ ia64*-hpux*)
     esac
 
     case "$target" in
     i*86-*)
         if test "$HAVE_64BIT_OS"; then
             AC_MSG_ERROR([You are targeting i386 but using the 64-bit compiler.])
         fi
 
-        if test $_MSC_VER -ge 1400; then
-            LDFLAGS="$LDFLAGS -SAFESEH"
-        fi
-
         if test -n "$GNU_CC"; then
             CFLAGS="$CFLAGS -mstackrealign -fno-keep-inline-dllexport"
             CXXFLAGS="$CXXFLAGS -mstackrealign -fno-keep-inline-dllexport"
         else
             AC_DEFINE(HAVE_STDCALL)
             DSO_LDOPTS="$DSO_LDOPTS -MACHINE:X86"
+            LDFLAGS="$LDFLAGS -SAFESEH"
         fi
 
     	AC_DEFINE(_X86_)
 	;;
     alpha-*)
     	AC_DEFINE(_ALPHA_)
 	;;
     mips-*)