diff --git a/src/base/bitfield.hh b/src/base/bitfield.hh
index ec1ffce..59b239a 100644
--- a/src/base/bitfield.hh
+++ b/src/base/bitfield.hh
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017 ARM Limited
+ * Copyright (c) 2017, 2019 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -293,4 +293,15 @@
     return value ? __builtin_ctz(value) : 32;
 }
 
+/**
+ * Count trailing zeros in a 64-bit value.
+ *
+ * @param An input value
+ * @return The number of trailing zeros or 64 if the value is zero.
+ */
+inline int ctz64(uint64_t value)
+{
+    return value ? __builtin_ctzll(value) : 64;
+}
+
 #endif // __BASE_BITFIELD_HH__