diff --git a/module/language/tree-il/compile-glil.scm b/module/language/tree-il/compile-glil.scm
index 86b610f..57a46c8 100644
--- a/module/language/tree-il/compile-glil.scm
+++ b/module/language/tree-il/compile-glil.scm
@@ -22,6 +22,7 @@
   #:use-module (system base syntax)
   #:use-module (system base pmatch)
   #:use-module (system base message)
+  #:use-module (srfi srfi-1)
   #:use-module (ice-9 receive)
   #:use-module (language glil)
   #:use-module (system vm instruction)
@@ -394,20 +395,28 @@
                             (cons (primitive-ref-name proc) (length args)))
                   (hash-ref *primcall-ops* (primitive-ref-name proc))))
          => (lambda (op)
-              (for-each comp-push args)
-              (emit-code src (make-glil-call op (length args)))
-              (case (instruction-pushes op)
-                ((0)
-                 (case context
-                   ((tail push vals) (emit-code #f (make-glil-void))))
-                 (maybe-emit-return))
-                ((1)
-                 (case context
-                   ((drop) (emit-code #f (make-glil-call 'drop 1))))
-                 (maybe-emit-return))
-                (else
-                 (error "bad primitive op: too many pushes"
-                        op (instruction-pushes op))))))
+              (if (every const? args)
+                  (let* ((proc (module-ref the-scm-module
+                                           (primitive-ref-name proc)))
+                         (args (map const-exp args)))
+                    ;; constant folding
+                    (emit-code src
+                               (make-glil-const (apply proc args))))
+                  (begin
+                    (for-each comp-push args)
+                    (emit-code src (make-glil-call op (length args)))
+                    (case (instruction-pushes op)
+                      ((0)
+                       (case context
+                         ((tail push vals) (emit-code #f (make-glil-void))))
+                       (maybe-emit-return))
+                      ((1)
+                       (case context
+                         ((drop) (emit-code #f (make-glil-call 'drop 1))))
+                       (maybe-emit-return))
+                      (else
+                       (error "bad primitive op: too many pushes"
+                              op (instruction-pushes op))))))))
         
         ;; da capo al fine
         ((and (lexical-ref? proc)