diff --git a/src/lib.rs b/src/lib.rs
index dd74009..db09ae1 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -246,19 +246,27 @@ impl std::error::Error for Error {}
 pub struct ThreadPriorityValue(u8);
 impl ThreadPriorityValue {
     /// The maximum value for a thread priority.
-    pub const MAX: u8 = 99;
+    pub const MAX: u8 = if cfg!(target_os = "vxworks") {
+        255
+    } else {
+        99
+    };
     /// The minimum value for a thread priority.
     pub const MIN: u8 = 0;
 }
 
 impl std::convert::TryFrom<u8> for ThreadPriorityValue {
-    type Error = &'static str;
+    type Error = String;
 
     fn try_from(value: u8) -> Result<Self, Self::Error> {
         if (Self::MIN..=Self::MAX).contains(&value) {
             Ok(Self(value))
         } else {
-            Err("The value is not in the range of [0;99]")
+            Err(format!(
+                "The value is not in the range of [{}; {}]",
+                Self::MIN,
+                Self::MAX
+            ))
         }
     }
 }
diff --git a/tests/unix.rs b/tests/unix.rs
index ff144c2..e699ef7 100644
--- a/tests/unix.rs
+++ b/tests/unix.rs
@@ -46,6 +46,7 @@ fn get_and_set_priority_with_normal_policies(
 #[cfg(any(
     target_os = "macos",
     target_os = "openbsd",
+    target_os = "vxworks",
     target_os = "freebsd",
     target_os = "netbsd"
 ))]
@@ -107,6 +108,7 @@ fn set_priority_with_normal_policy_but_with_invalid_value(#[case] policy: Thread
 #[cfg(any(
     target_os = "macos",
     target_os = "openbsd",
+    target_os = "vxworks",
     target_os = "freebsd",
     target_os = "netbsd"
 ))]