diff --git a/src/syscall/syscall_unix.go b/src/syscall/syscall_unix.go
index faaa432136..1b66e3bb11 100644
--- a/src/syscall/syscall_unix.go
+++ b/src/syscall/syscall_unix.go
@@ -21,11 +21,8 @@ var (
 )
 
 const (
-	darwin64Bit    = runtime.GOOS == "darwin" && sizeofPtr == 8
-	dragonfly64Bit = runtime.GOOS == "dragonfly" && sizeofPtr == 8
-	netbsd32Bit    = runtime.GOOS == "netbsd" && sizeofPtr == 4
-	solaris64Bit   = runtime.GOOS == "solaris" && sizeofPtr == 8
-	illumos64Bit   = runtime.GOOS == "illumos" && sizeofPtr == 8
+	darwin64Bit = runtime.GOOS == "darwin" && sizeofPtr == 8
+	netbsd32Bit = runtime.GOOS == "netbsd" && sizeofPtr == 4
 )
 
 func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)