diff --git a/src/apply.xsl b/src/apply.xsl
index eb4f868..6f76bcf 100644
--- a/src/apply.xsl
+++ b/src/apply.xsl
@@ -193,4 +193,20 @@
   </message>
 </template>
 
+
+<!--
+  Attempt to retrieve arity of delayed function
+
+  The input must be a function reference.  If the arity cannot be
+  determined, -1 is returned.
+-->
+<function name="f:arity" as="xs:decimal">
+  <param name="fnref" as="element()" />
+
+  <sequence select="if ( $fnref/@arity ) then
+                      $fnref/@arity
+                    else
+                      -1" />
+</function>
+
 </stylesheet>
diff --git a/src/transform/apply-gen.xsl b/src/transform/apply-gen.xsl
index 1d7241b..732358c 100644
--- a/src/transform/apply-gen.xsl
+++ b/src/transform/apply-gen.xsl
@@ -112,8 +112,6 @@
        dependencies and simply specify the full namespace URI -->
   <variable name="name-resolv"
             select="resolve-QName( @name, . )" />
-  <variable name="local-name"
-            select="substring-after( @name, ':' )" />
   <variable name="ns-prefix"
             select="substring-before( @name, ':' )" />
   <variable name="ns"
@@ -121,7 +119,7 @@
                       $ns-prefix, . )" />
 
   <sequence select="fgen:create-func(
-                      $name-resolv, $local-name, $ns-prefix, $ns )" />
+                      ., $name-resolv, $ns-prefix, $ns )" />
   <sequence select="fgen:create-tpl(
                       $name-resolv, ., $ns-prefix, $ns )" />
 </template>
@@ -147,17 +145,23 @@
   mode `f:apply' to invoke the associated application template.
 -->
 <function name="fgen:create-func">
+  <param name="fnref"       as="element(xsl:function)" />
   <param name="name-resolv" as="xs:QName" />
-  <param name="local-name"  as="xs:string" />
   <param name="ns-prefix"   as="xs:string" />
   <param name="ns"          as="xs:anyURI" />
 
+  <variable name="local-name"
+            select="substring-after( $fnref/@name, ':' )" />
+
   <out:function name="{$name-resolv}" as="element()">
     <namespace name="{$ns-prefix}"
                select="$ns" />
 
     <element name="{$local-name}"
-             namespace="{$ns}" />
+             namespace="{$ns}">
+      <attribute name="arity"
+                 select="count( $fnref/xsl:param )" />
+    </element>
   </out:function>
 </function>
 
diff --git a/test/apply.xspec b/test/apply.xspec
index 030ac8a..865ba1b 100644
--- a/test/apply.xspec
+++ b/test/apply.xspec
@@ -172,4 +172,41 @@
       </scenario>
     </scenario>
   </scenario>
+
+
+  <scenario label="f:arity">
+    <scenario label="given a proper function reference">
+      <variable name="test-arity"
+                select="5" />
+
+      <!-- test our format directly; do not rely on the
+           apply-gen code -->
+      <variable name="fnref">
+        <foo:bar arity="{$test-arity}" />
+      </variable>
+
+      <call function="f:arity">
+        <param name="fnref"
+               select="$fnref" />
+      </call>
+
+      <expect label="provides function arity"
+              test="$x:result = $test-arity" />
+    </scenario>
+
+
+    <scenario label="given a function reference with no defined arity">
+      <variable name="fnref">
+        <foo:bar />
+      </variable>
+
+      <call function="f:arity">
+        <param name="fnref"
+               select="$fnref" />
+      </call>
+
+      <expect label="returns -1"
+              test="$x:result = -1" />
+    </scenario>
+  </scenario>
 </description>
diff --git a/test/transform/apply-gen-test.xsl b/test/transform/apply-gen-test.xsl
index ecf6c15..3e79ed3 100644
--- a/test/transform/apply-gen-test.xsl
+++ b/test/transform/apply-gen-test.xsl
@@ -30,6 +30,8 @@
   <!-- SUT -->
   <import href="../../src/transform/apply-gen.xsl" />
 
+  <import href="../../src/apply.xsl" />
+
   <!-- input stylesheet -->
   <import href="apply-gen-test-in.xsl" />
 
diff --git a/test/transform/apply-gen.xspec b/test/transform/apply-gen.xspec
index 5409e87..3d84649 100644
--- a/test/transform/apply-gen.xspec
+++ b/test/transform/apply-gen.xspec
@@ -22,6 +22,7 @@
 
 <description xmlns="http://www.jenitennison.com/xslt/xspec"
              xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+             xmlns:f="http://www.lovullo.com/hoxsl/apply"
              xmlns:foo="http://www.lovullo.com/_junk"
              stylesheet="apply-gen-test.xsl">
 
@@ -49,9 +50,7 @@
     <!-- the generated node is simply the same name and namespace as
          the function -->
     <expect label="generated function produces function node"
-            context="xsl:stylesheet/xsl:function/*">
-      <foo:bar />
-    </expect>
+            test="exists( xsl:stylesheet/xsl:function/foo:bar )" />
 
 
     <!-- more detailed tests below -->
@@ -157,14 +156,16 @@
 
        Exciting! -->
   <scenario label="given a generated document">
-    <!-- calling the generated nullary -->
-    <call function="foo:apply-add-two">
-      <param name="x" select="2" />
-      <param name="y" select="3" />
-    </call>
+    <scenario label="with a processed function">
+      <!-- calling the generated nullary -->
+      <call function="foo:apply-add-two">
+        <param name="x" select="2" />
+        <param name="y" select="3" />
+      </call>
 
-    <expect label="applying template to nullary yields proper result"
-            test="$x:result = 5" />
+      <expect label="applying template to nullary yields proper result"
+              test="$x:result = 5" />
+    </scenario>
 
 
     <!-- ensure that multiple functions are processed -->
@@ -177,5 +178,17 @@
       <expect label="applying template to nullary yields proper result"
               test="$x:result = -1" />
     </scenario>
+
+
+    <!-- note that this _does not_ test f:arity itself: it is intended
+         to test that the arity datum is properly generated -->
+    <scenario label="f:arity">
+      <call function="f:arity">
+        <param name="fnref" select="foo:sub-two()" />
+      </call>"
+
+      <expect label="is able to determine arity"
+              test="$x:result = 2" />
+    </scenario>
   </scenario>
 </description>