diff --git a/javaobj/v1/unmarshaller.py b/javaobj/v1/unmarshaller.py
index 4895a26..3d0efb8 100644
--- a/javaobj/v1/unmarshaller.py
+++ b/javaobj/v1/unmarshaller.py
@@ -65,11 +65,7 @@
     hexdump,
 )
 
-# Numpy array support
-try:
-    import numpy
-except ImportError:
-    numpy = None
+numpy = None  # Imported only when really used
 
 # ------------------------------------------------------------------------------
 
@@ -113,6 +109,15 @@ def __init__(self, stream, use_numpy_arrays=False):
         """
         self.use_numpy_arrays = use_numpy_arrays
 
+        # Numpy array support
+        if self.use_numpy_arrays:
+            try:
+                global numpy
+                import numpy as np
+                numpy = np
+            except ImportError:
+                pass
+
         # Check stream
         if stream is None:
             raise IOError("No input stream given")