diff --git a/compat/mingw.c b/compat/mingw.c
index 738f0a826a..43f67080bc 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -1663,6 +1663,8 @@ char *mingw_getenv(const char *name)
 	if (!w_key)
 		die("Out of memory, (tried to allocate %u wchar_t's)", len_key);
 	xutftowcs(w_key, name, len_key);
+	/* GetEnvironmentVariableW() only sets the last error upon failure */
+	SetLastError(ERROR_SUCCESS);
 	len_value = GetEnvironmentVariableW(w_key, w_value, ARRAY_SIZE(w_value));
 	if (!len_value && GetLastError() == ERROR_ENVVAR_NOT_FOUND) {
 		free(w_key);