diff --git a/libraries/AP_Math/AP_Math.cpp b/libraries/AP_Math/AP_Math.cpp
index c68c7491f4..c0289c6a80 100644
--- a/libraries/AP_Math/AP_Math.cpp
+++ b/libraries/AP_Math/AP_Math.cpp
@@ -190,8 +190,8 @@ uint16_t get_random16(void)
 {
     static uint32_t m_z = 1234;
     static uint32_t m_w = 76542;
-    m_z = 36969 * (m_z & 65535) + (m_z >> 16);
-    m_w = 18000 * (m_w & 65535) + (m_w >> 16);
+    m_z = 36969 * (m_z & 0xFFFFu) + (m_z >> 16);
+    m_w = 18000 * (m_w & 0xFFFFu) + (m_w >> 16);
     return ((m_z << 16) + m_w) & 0xFFFF;
 }