diff --git a/src/ansi-c/parser.y b/src/ansi-c/parser.y
index 25e63ffdc80..2691142097d 100644
--- a/src/ansi-c/parser.y
+++ b/src/ansi-c/parser.y
@@ -26,6 +26,19 @@ extern char *yyansi_ctext;
 
 #include "ansi_c_y.tab.h"
 
+#ifdef _MSC_VER
+// possible loss of data
+#pragma warning(disable:4242)
+// possible loss of data
+#pragma warning(disable:4244)
+// signed/unsigned mismatch
+#pragma warning(disable:4365)
+// switch with default but no case labels
+#pragma warning(disable:4065)
+// unreachable code
+#pragma warning(disable:4702)
+#endif
+
 // statements have right recursion, deep nesting of statements thus
 // requires more stack space
 #define YYMAXDEPTH 25600
diff --git a/src/ansi-c/scanner.l b/src/ansi-c/scanner.l
index 1695539a65f..71eae243eba 100644
--- a/src/ansi-c/scanner.l
+++ b/src/ansi-c/scanner.l
@@ -4,6 +4,14 @@
 
 %{
 
+#if defined _MSC_VER
+// signed/unsigned mismatch
+#pragma warning(disable:4365)
+// macro re-definition: flex conditonally defines INT32_MAX et al. and thus
+// they are set before library headers get to define them
+#pragma warning(disable:4005)
+#endif
+
 /*
  * This scanner is based on:
  *
diff --git a/src/assembler/scanner.l b/src/assembler/scanner.l
index 816e61616dc..a050bd048ab 100755
--- a/src/assembler/scanner.l
+++ b/src/assembler/scanner.l
@@ -5,6 +5,14 @@
 
 %{
 
+#if defined _MSC_VER
+// signed/unsigned mismatch
+#pragma warning(disable:4365)
+// macro re-definition: flex conditonally defines INT32_MAX et al. and thus
+// they are set before library headers get to define them
+#pragma warning(disable:4005)
+#endif
+
 #define PARSER assembler_parser
 #define YYSTYPE unsigned
 #undef  ECHO
diff --git a/src/jsil/parser.y b/src/jsil/parser.y
index 12c9385d8fa..a3a0563dd16 100644
--- a/src/jsil/parser.y
+++ b/src/jsil/parser.y
@@ -16,6 +16,20 @@ extern char *yyjsiltext;
 #include <util/string_constant.h>
 
 #include "jsil_y.tab.h"
+
+#ifdef _MSC_VER
+// possible loss of data
+#pragma warning(disable:4242)
+// possible loss of data
+#pragma warning(disable:4244)
+// signed/unsigned mismatch
+#pragma warning(disable:4365)
+// switch with default but no case labels
+#pragma warning(disable:4065)
+// unreachable code
+#pragma warning(disable:4702)
+#endif
+
 /*** token declaration **************************************************/
 %}
 
diff --git a/src/jsil/scanner.l b/src/jsil/scanner.l
index c8e5c46d626..2eedc4c607d 100755
--- a/src/jsil/scanner.l
+++ b/src/jsil/scanner.l
@@ -6,6 +6,14 @@
 
 %{
 
+#if defined _MSC_VER
+// signed/unsigned mismatch
+#pragma warning(disable:4365)
+// macro re-definition: flex conditonally defines INT32_MAX et al. and thus
+// they are set before library headers get to define them
+#pragma warning(disable:4005)
+#endif
+
 #include <util/expr.h>
 
 #include <ansi-c/literals/convert_float_literal.h>
diff --git a/src/json/parser.y b/src/json/parser.y
index 044fce1eb1f..9d17ef51242 100644
--- a/src/json/parser.y
+++ b/src/json/parser.y
@@ -1,4 +1,17 @@
 %{
+#ifdef _MSC_VER
+// possible loss of data
+#pragma warning(disable:4242)
+// possible loss of data
+#pragma warning(disable:4244)
+// signed/unsigned mismatch
+#pragma warning(disable:4365)
+// switch with default but no case labels
+#pragma warning(disable:4065)
+// unreachable code
+#pragma warning(disable:4702)
+#endif
+
 // Strictly follows http://www.json.org/
 %}
 
diff --git a/src/json/scanner.l b/src/json/scanner.l
index ad854544950..fc29b2e4456 100755
--- a/src/json/scanner.l
+++ b/src/json/scanner.l
@@ -12,6 +12,14 @@
 
 %{
 
+#if defined _MSC_VER
+// signed/unsigned mismatch
+#pragma warning(disable:4365)
+// macro re-definition: flex conditonally defines INT32_MAX et al. and thus
+// they are set before library headers get to define them
+#pragma warning(disable:4005)
+#endif
+
 #define PARSER json_parser
 
 #include "json_parser.h"
diff --git a/src/xmllang/parser.y b/src/xmllang/parser.y
index 0ef8686fb8e..0580ca01a27 100644
--- a/src/xmllang/parser.y
+++ b/src/xmllang/parser.y
@@ -12,6 +12,18 @@ int yyxmlerror(const std::string &error)
   return 0;
 }
 
+#ifdef _MSC_VER
+// possible loss of data
+#pragma warning(disable:4242)
+// possible loss of data
+#pragma warning(disable:4244)
+// signed/unsigned mismatch
+#pragma warning(disable:4365)
+// switch with default but no case labels
+#pragma warning(disable:4065)
+// unreachable code
+#pragma warning(disable:4702)
+#endif
 %}
 
 %error-verbose
diff --git a/src/xmllang/scanner.l b/src/xmllang/scanner.l
index 5726c75afee..ef4c439d5a0 100755
--- a/src/xmllang/scanner.l
+++ b/src/xmllang/scanner.l
@@ -6,6 +6,14 @@
 
 %{
 
+#if defined _MSC_VER
+// signed/unsigned mismatch
+#pragma warning(disable:4365)
+// macro re-definition: flex conditonally defines INT32_MAX et al. and thus
+// they are set before library headers get to define them
+#pragma warning(disable:4005)
+#endif
+
 #include <cctype>
 #include <cstring>
 #include <cstdlib>