diff --git a/tools/aidl/aidl_language.cpp b/tools/aidl/aidl_language.cpp
index e2540658b6200..4eb3faecb5741 100644
--- a/tools/aidl/aidl_language.cpp
+++ b/tools/aidl/aidl_language.cpp
@@ -5,6 +5,13 @@
 #include <string>
 #include <iostream>
 
+#ifdef _WIN32
+int isatty(int  fd)
+{
+    return (fd == 0);
+}
+#endif
+
 using std::string;
 using std::cerr;
 using std::endl;
diff --git a/tools/aidl/aidl_language_l.l b/tools/aidl/aidl_language_l.l
index b8e53a83ebd88..540b550035fff 100644
--- a/tools/aidl/aidl_language_l.l
+++ b/tools/aidl/aidl_language_l.l
@@ -7,13 +7,6 @@
 
 extern YYSTYPE yylval;
 
-#ifdef _WIN32
-static inline int isatty(int fd)
-{
-  return 0;
-}
-#endif
-
 // comment and whitespace handling
 // these functions save a copy of the buffer
 static void begin_extra_text(unsigned lineno, which_extra_text which);