diff --git a/src/glsl/glcpp/glcpp-lex.l b/src/glsl/glcpp/glcpp-lex.l
index 68e44eb7902..86618870885 100644
--- a/src/glsl/glcpp/glcpp-lex.l
+++ b/src/glsl/glcpp/glcpp-lex.l
@@ -34,6 +34,10 @@
 int glcpp_get_column  (yyscan_t yyscanner);
 void glcpp_set_column (int  column_no , yyscan_t yyscanner);
 
+#ifdef _MSC_VER
+#define YY_NO_UNISTD_H
+#endif
+
 #define YY_NO_INPUT
 
 #define YY_USER_ACTION                                          \
diff --git a/src/glsl/glsl_lexer.ll b/src/glsl/glsl_lexer.ll
index e4c469f9e0a..cfd89261757 100644
--- a/src/glsl/glsl_lexer.ll
+++ b/src/glsl/glsl_lexer.ll
@@ -29,6 +29,10 @@
 
 static int classify_identifier(struct _mesa_glsl_parse_state *, const char *);
 
+#ifdef _MSC_VER
+#define YY_NO_UNISTD_H
+#endif
+
 #define YY_USER_ACTION						\
    do {								\
       yylloc->source = 0;					\