diff --git a/fun/semantics.rkt b/fun/semantics.rkt
index 870b07b..b303b77 100644
--- a/fun/semantics.rkt
+++ b/fun/semantics.rkt
@@ -14,7 +14,7 @@
          let let*
 	 if and or not true false eq? equal?
 	 begin
-         ivec vlen vec-ref
+         ivec vec-len vec-ref
          pair left right pair?
 	 + - * /
 	 zero?
@@ -77,17 +77,17 @@
      (test/pred L (lambda (v) (not (equal~? v R))))]))
 
 (define ivec vector-immutable)
-(define vlen vector-length)
+(define vec-len vector-length)
 (define vec-ref vector-ref)
 
 (define (pair a b)
   (ivec a b))
 (define (left p)
-  (unless (= (vlen p) 2)
+  (unless (= (vec-len p) 2)
     (error 'left "argument must be a pair: ~a" p))
   (vec-ref p 0))
 (define (right p)
-  (unless (= (vlen p) 2)
+  (unless (= (vec-len p) 2)
     (error 'right "argument must be a pair: ~a" p))
   (vec-ref p 1))
-(define (pair? v) (and (vector? v) (= (vlen v) 2)))
+(define (pair? v) (and (vector? v) (= (vec-len v) 2)))
diff --git a/scribblings/smol.scrbl b/scribblings/smol.scrbl
index 3d114a4..a21d36e 100644
--- a/scribblings/smol.scrbl
+++ b/scribblings/smol.scrbl
@@ -54,12 +54,12 @@ exotic quoted forms. (If you don't know what these are, ignore them.)
 
 @deftogether[(
 @defproc[(ivec (elem Any) ...) Vec]
-@defproc[(vlen (expr Vec)) Number]
+@defproc[(vec-len (expr Vec)) Number]
 @defproc[(vec-ref (vec-expr Vec) (idx-expr Number)) Any]
 )]{
 The @code{ivec} operation builds an @emph{immutable} vector of the
 elements in @code{elem}. Vector elements need not be of the same
-type. @code{vlen} computes its length, while @code{vec-ref} indexes
+type. @code{vec-len} computes its length, while @code{vec-ref} indexes
 into it (starting from @code{0}).
 }
 
diff --git a/state/semantics.rkt b/state/semantics.rkt
index 12f5afd..b753eed 100644
--- a/state/semantics.rkt
+++ b/state/semantics.rkt
@@ -19,10 +19,10 @@
 (define (mpair a b)
   (mvec a b))
 (define (set-left! p v)
-  (unless (= (vlen p) 2)
+  (unless (= (vec-len p) 2)
     (error 'set-left! "the first argument must be a pair: ~a" p))
   (vector-set! p 0 v))
 (define (set-right! p v)
-  (unless (= (vlen p) 2)
+  (unless (= (vec-len p) 2)
     (error 'set-right! "the first argument must be a pair: ~a" p))
   (vector-set! p 1 v))
diff --git a/state/tests/all.rkt b/state/tests/all.rkt
index 8753de4..af33846 100644
--- a/state/tests/all.rkt
+++ b/state/tests/all.rkt
@@ -11,7 +11,7 @@
 (test (left p) "x")
 (test (right p) "y")
 
-(test (vlen p) 2)
+(test (vec-len p) 2)
 (test (pair? p) true)
 (test (pair? (mvec "g" "h")) true)