diff --git a/src/runtime/debug.go b/src/runtime/debug.go
new file mode 100644
index 00000000..8a69c6e2
--- /dev/null
+++ b/src/runtime/debug.go
@@ -0,0 +1,10 @@
+package runtime
+
+// NumCPU returns the number of logical CPUs usable by the current process.
+//
+// The set of available CPUs is checked by querying the operating system
+// at process startup. Changes to operating system CPU allocation after
+// process startup are not reflected.
+func NumCPU() int {
+	return 1
+}