diff --git a/net/test/bpf.py b/net/test/bpf.py
index 24dc7a1..7625265 100755
--- a/net/test/bpf.py
+++ b/net/test/bpf.py
@@ -21,15 +21,23 @@
 import cstruct
 import net_test
 import socket
+import platform
 
 # __NR_bpf syscall numbers for various architectures.
+# NOTE: If python inherited COMPAT_UTS_MACHINE, uname's 'machine' field will
+# return the 32-bit architecture name, even if python itself is 64-bit. To work
+# around this problem and pick the right syscall nr, we can additionally check
+# the bitness of the python interpreter. Assume that the 64-bit architectures
+# are not running with COMPAT_UTS_MACHINE and must be 64-bit at all times.
 # TODO: is there a better way of doing this?
 __NR_bpf = {
-    "aarch64": 280,
-    "armv8l": 386,
-    "i686" : 357,
-    "x86_64": 321,
-}[os.uname()[4]]
+    "aarch64-64bit": 280,
+    "armv8l-32bit": 386,
+    "armv8l-64bit": 280,
+    "i686-32bit": 357,
+    "i686-64bit": 321,
+    "x86_64-64bit": 321,
+}[os.uname()[4] + "-" + platform.architecture()[0]]
 
 LOG_LEVEL = 1
 LOG_SIZE = 65536