diff --git a/sys/cddl/contrib/opensolaris/uts/common/sys/dtrace.h b/sys/cddl/contrib/opensolaris/uts/common/sys/dtrace.h
--- a/sys/cddl/contrib/opensolaris/uts/common/sys/dtrace.h
+++ b/sys/cddl/contrib/opensolaris/uts/common/sys/dtrace.h
@@ -2427,9 +2427,7 @@
 
 #endif /* _KERNEL */
 
-#if defined(__i386) || defined(__amd64) || defined (__riscv)
 extern int dtrace_instr_size(uint8_t *instr);
-#endif
 
 #if defined(__i386) || defined(__amd64)
 extern int dtrace_dis_get_byte(void *p);