diff --git a/virt-what.spec b/virt-what.spec
index 2fd932c..278022c 100644
--- a/virt-what.spec
+++ b/virt-what.spec
@@ -1,6 +1,6 @@
 Name:           virt-what
 Version:        1.15
-Release:        3%{?dist}
+Release:        4%{?dist}
 Summary:        Detect if we are running in a virtual machine
 License:        GPLv2+
 
@@ -21,6 +21,9 @@ Requires:       dmidecode
 %endif
 Requires:       util-linux
 
+# Runs the 'which' program to find the helper.
+Requires:       which
+
 
 %description
 virt-what is a shell script which can be used to detect if the program
@@ -77,6 +80,9 @@ make check
 
 
 %changelog
+* Tue Jun 14 2016 Richard W.M. Jones <rjones@redhat.com> - 1.15-4
+- Require 'which' program.
+
 * Fri Feb 05 2016 Fedora Release Engineering <releng@fedoraproject.org> - 1.15-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_24_Mass_Rebuild