diff --git a/database.py b/database.py
index c3b8f4d..8532bc0 100644
--- a/database.py
+++ b/database.py
@@ -245,7 +245,7 @@ class Database(Profiler):
         while not allocated:
             cache_size = 2**cache_width
             try:
-                self.ip4cache = numpy.zeros(cache_size, dtype=numpy.bool)
+                self.ip4cache = numpy.zeros(cache_size, dtype=bool)
             except MemoryError:
                 self.log.exception(
                     "Could not allocate cache. Retrying a smaller one.")