diff --git a/src/pkg/runtime/sys_freebsd_386.s b/src/pkg/runtime/sys_freebsd_386.s
index d8dc40d8f3..9f31e253f1 100644
--- a/src/pkg/runtime/sys_freebsd_386.s
+++ b/src/pkg/runtime/sys_freebsd_386.s
@@ -299,5 +299,9 @@ TEXT runtime·sysctl(SB),7,$28
 	MOVL	$0, AX
 	RET
 
+TEXT runtime·osyield(SB),7,$-4
+	MOVL	$331, AX		// sys_sched_yield
+	INT	$0x80
+	RET
 
 GLOBL runtime·tlsoffset(SB),$4
diff --git a/src/pkg/runtime/sys_freebsd_amd64.s b/src/pkg/runtime/sys_freebsd_amd64.s
index dcd55855a9..b14b66556c 100644
--- a/src/pkg/runtime/sys_freebsd_amd64.s
+++ b/src/pkg/runtime/sys_freebsd_amd64.s
@@ -229,3 +229,7 @@ TEXT runtime·sysctl(SB),7,$0
 	MOVL	$0, AX
 	RET
 
+TEXT runtime·osyield(SB),7,$-4
+	MOVL	$331, AX		// sys_sched_yield
+	INT	$0x80
+	RET
diff --git a/src/pkg/runtime/thread_freebsd.c b/src/pkg/runtime/thread_freebsd.c
index 1c48865a23..06e3a59d00 100644
--- a/src/pkg/runtime/thread_freebsd.c
+++ b/src/pkg/runtime/thread_freebsd.c
@@ -154,9 +154,3 @@ runtime·sigpanic(void)
 	}
 	runtime·panicstring(runtime·sigtab[g->sig].name);
 }
-
-// TODO: fill this in properly.
-void
-runtime·osyield(void)
-{
-}