Index: head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
===================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
+++ head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c
@@ -4391,8 +4391,8 @@
 			break;
 		}
 		l.lx = dtrace_loadptr(tupregs[0].dttk_value);
-		LOCK_CLASS(l.li)->lc_owner(l.li, &lowner);
-		regs[rd] = (lowner == curthread);
+		regs[rd] = LOCK_CLASS(l.li)->lc_owner(l.li, &lowner) &&
+		    lowner != NULL;
 		break;
 
 	case DIF_SUBR_RW_ISWRITER:
@@ -4403,8 +4403,8 @@
 			break;
 		}
 		l.lx = dtrace_loadptr(tupregs[0].dttk_value);
-		regs[rd] = LOCK_CLASS(l.li)->lc_owner(l.li, &lowner) &&
-		    lowner != NULL;
+		LOCK_CLASS(l.li)->lc_owner(l.li, &lowner);
+		regs[rd] = (lowner == curthread);
 		break;
 #endif /* illumos */