diff --git a/themes/base.theme.bash b/themes/base.theme.bash
index 629e81d..44c34ab 100644
--- a/themes/base.theme.bash
+++ b/themes/base.theme.bash
@@ -34,7 +34,7 @@
   if [[ -f .git/HEAD ]]; then SCM=$SCM_GIT
   elif [[ -n "$(git symbolic-ref HEAD 2> /dev/null)" ]]; then SCM=$SCM_GIT
   elif [[ -d .hg ]]; then SCM=$SCM_HG
-  elif [[ -n "$(hg root 2> /dev/null)" ]]; then SCM=$SCM_HG
+  elif which hg &> /dev/null && [[ -n "$(hg root 2> /dev/null)" ]]; then SCM=$SCM_HG
   elif [[ -d .svn ]]; then SCM=$SCM_SVN
   else SCM=$SCM_NONE
   fi