--- ./Sources/UInt256+arc4random.swift.org	2020-08-23 16:52:45.000000000 +0900
+++ ./Sources/UInt256+arc4random.swift	2020-08-31 08:47:10.760000000 +0900
@@ -32,7 +32,11 @@
 
     func generateRandom(within highBits: UInt32) -> UInt64 {
         let high: UInt32 = arc4random_uniform(highBits)
+#if false//!os(Linux)
         let low: UInt32 = arc4random()
+#else
+        let low: UInt32 = UInt32.random(in: 0...UInt32.max)
+#endif
         let result: UInt64 = UInt64(high) << 32 + UInt64(low)
         return result
     }
@@ -65,8 +69,13 @@
 }
 
 func arc4random64() -> UInt64 {
+#if false//!os(Linux)
     let high: UInt32 = arc4random()
     let low: UInt32 = arc4random()
+#else
+    let high: UInt32 = UInt32.random(in: 0...UInt32.max)
+    let low: UInt32 = UInt32.random(in: 0...UInt32.max)
+#endif
     let result: UInt64 = UInt64(high) << 32 + UInt64(low)
     return result
 }
--- ./makefile.org	2020-08-28 18:02:02.000000000 +0900
+++ ./makefile	2020-08-31 09:07:03.650000000 +0900
@@ -2,6 +2,9 @@
 EXES=$(SRCS:%.swift=%)
 
 SWIFTCFLAGS=-O
+ifeq ($(shell uname -s),Linux)
+SWIFTCFLAGS=
+endif
 
 all: $(EXES) $(EXES:%=outs/%.out)