diff --git a/plugins/primus_lisp/primus_lisp_semantic_primitives.ml b/plugins/primus_lisp/primus_lisp_semantic_primitives.ml
index ee4b2e9bc..4fddc684d 100644
--- a/plugins/primus_lisp/primus_lisp_semantic_primitives.ml
+++ b/plugins/primus_lisp/primus_lisp_semantic_primitives.ml
@@ -256,6 +256,10 @@ let export = Primus.Lisp.Type.Spec.[
     "get-current-program-counter", unit @-> int,
     "(get-current-program-counter) is an alias to (get-program-counter)";
 
+    "get-instruction-length", unit @-> int,
+    "(get-instruction-length) returns the length of the current instruction \
+     in bytes.";
+
     "set-symbol-value", tuple [any; a] @-> a,
     "(set-symbol-value S X) sets the value of the symbol S to X.
          Returns X";
@@ -839,6 +843,12 @@ module Primitives(CT : Theory.Core)(T : Target) = struct
     | None -> !!(empty s)
     | Some addr -> forget@@const_int s addr
 
+  let get_instruction_length s lbl =
+    let open Bap.Std in
+    KB.collect Memory.slot lbl >>= function
+    | None -> !!(empty s)
+    | Some mem -> forget@@int s (Memory.length mem)
+
   let require_symbol v k =
     match symbol v with
     | Some name -> k name
@@ -1479,6 +1489,7 @@ module Primitives(CT : Theory.Core)(T : Target) = struct
     | "store-word",_-> data@@store_word t args
     | "get-program-counter",[]
     | "get-current-program-counter",[] -> pure@@get_pc s lbl
+    | "get-instruction-length",[] -> pure@@get_instruction_length s lbl
     | "set-symbol-value",[sym;x] -> data@@set_symbol t sym x
     | "symbol-concat",syms -> pure@@symbol_concat s syms
     | "symbol",[x] -> pure@@mksymbol s x
diff --git a/plugins/primus_lisp/site-lisp/llvm-x86-64-floats.lisp b/plugins/primus_lisp/site-lisp/llvm-x86-64-floats.lisp
index e8980b26d..a75b833c5 100644
--- a/plugins/primus_lisp/site-lisp/llvm-x86-64-floats.lisp
+++ b/plugins/primus_lisp/site-lisp/llvm-x86-64-floats.lisp
@@ -24,7 +24,7 @@
 
 (defun reg-val (reg)
   (case (reg-name reg)
-    'RIP (+ (get-current-program-counter) 8)
+    'RIP (+ (get-current-program-counter) (get-instruction-length))
     'RSP RSP
     'RBP RBP
     (error "unknown register")))
diff --git a/plugins/x86/semantics/x86-64.lisp b/plugins/x86/semantics/x86-64.lisp
index d2551ccda..045c5fc5b 100644
--- a/plugins/x86/semantics/x86-64.lisp
+++ b/plugins/x86/semantics/x86-64.lisp
@@ -24,7 +24,7 @@
 
 (defun reg# (reg)
   (if (is-rip reg)
-      (+ (get-program-counter) 8)
+      (+ (get-program-counter) (get-instruction-length))
     reg))
 
 (defun load-mem (reg off)
@@ -478,4 +478,4 @@
   (set rd (opo (opi rn rm))))
 
 (defmacro bitwise-rrm (set opo opi rd rn ptr off)
-  (set rd (opo (opi rn (load-bits (word-width (unquote rn)) (+ ptr off))))))
+  (set rd (opo (opi rn (load-bits (word-width (unquote rn)) (+ (reg# ptr) off))))))