diff --git a/asprintf.c b/asprintf.c
index 759dbee..d623bf2 100644
--- a/asprintf.c
+++ b/asprintf.c
@@ -9,8 +9,8 @@
 int vasprintf(char** pbuffer, const char* format, va_list ap)
 {
     va_list ap2;
-    size_t len;
-    
+    int len;
+
 #if defined(vxWorks)
     FILE* f;
     /* print to null device to get required buffer length */
diff --git a/asprintf.h b/asprintf.h
index 7625d11..35514bf 100644
--- a/asprintf.h
+++ b/asprintf.h
@@ -4,6 +4,10 @@
 extern "C" {
 #endif
 #include <stdarg.h>
+#ifndef __GNUC__
+#define __attribute__(arg)
+#endif
+
 int asprintf(char** pbuffer, const char* format, ...) __attribute__((format(printf,2,3)));
 int vasprintf(char** pbuffer, const char* format, va_list ap) __attribute__((format(printf,2,0)));
 #ifdef __cplusplus