errorhandling for calling GetFileAttributesA GetFileAttributesW
diff --git a/lib/zip_source_win32a.c b/lib/zip_source_win32a.c
index e47cadd..3e7f391 100644
--- a/lib/zip_source_win32a.c
+++ b/lib/zip_source_win32a.c
@@ -113,7 +113,7 @@
 	return -1;
 
     DWORD attributes = GetFileAttributesA(ctx->fname);
-    if (!attributes)
+    if (INVALID_FILE_ATTRIBUTES == attributes)
 	return -1;
 
     if (FILE_ATTRIBUTE_TEMPORARY & attributes) {
diff --git a/lib/zip_source_win32w.c b/lib/zip_source_win32w.c
index b39f509..9900794 100644
--- a/lib/zip_source_win32w.c
+++ b/lib/zip_source_win32w.c
@@ -137,7 +137,7 @@
 	return -1;
 
     DWORD attributes = GetFileAttributesW(ctx->fname);
-    if (!attributes)
+    if (INVALID_FILE_ATTRIBUTES == attributes)
 	return -1;
 
     if (FILE_ATTRIBUTE_TEMPORARY & attributes) {