diff --git a/tests/feature_check/target_info.py b/tests/feature_check/target_info.py
index 962ebf4154..5367eb6a47 100644
--- a/tests/feature_check/target_info.py
+++ b/tests/feature_check/target_info.py
@@ -20,6 +20,7 @@ arch = [
     "xtensawin",
     "rv32imc",
 ][sys_mpy >> 10]
+build = getattr(sys.implementation, "_build", "unknown")
 thread = getattr(sys.implementation, "_thread", None)
 
 # Detect how many bits of precision the floating point implementation has.
@@ -33,4 +34,4 @@ try:
 except NameError:
     float_prec = 0
 
-print(platform, arch, thread, float_prec, len("α") == 1)
+print(platform, arch, build, thread, float_prec, len("α") == 1)
diff --git a/tests/run-tests.py b/tests/run-tests.py
index 2d02e6b23c..c434cd6fc1 100755
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -291,7 +291,7 @@ def detect_test_platform(pyb, args):
     output = run_feature_check(pyb, args, "target_info.py")
     if output.endswith(b"CRASH"):
         raise ValueError("cannot detect platform: {}".format(output))
-    platform, arch, thread, float_prec, unicode = str(output, "ascii").strip().split()
+    platform, arch, build, thread, float_prec, unicode = str(output, "ascii").strip().split()
     if arch == "None":
         arch = None
     inlineasm_arch = detect_inline_asm_arch(pyb, args)
@@ -305,6 +305,7 @@ def detect_test_platform(pyb, args):
     if arch and not args.mpy_cross_flags:
         args.mpy_cross_flags = "-march=" + arch
     args.inlineasm_arch = inlineasm_arch
+    args.build = build
     args.thread = thread
     args.float_prec = float_prec
     args.unicode = unicode