diff --git a/letsencrypt-auto-source/letsencrypt-auto b/letsencrypt-auto-source/letsencrypt-auto
index 4ee16af95..ea3f7a4bb 100755
--- a/letsencrypt-auto-source/letsencrypt-auto
+++ b/letsencrypt-auto-source/letsencrypt-auto
@@ -345,20 +345,27 @@ BootstrapFreeBsd() {
 
 BootstrapMac() {
   if ! hash brew 2>/dev/null; then
-      echo "Homebrew Not Installed\nDownloading..."
+      echo "Homebrew not installed.\nDownloading..."
       ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
   fi
 
-  brew install augeas
-  brew install dialog
+  if [ -z "$(brew list --versions augeas)" ]; then
+      echo "augeas not installed.\nInstalling augeas from Homebrew..."
+      brew install augeas
+  fi
+
+  if [ -z "$(brew list --versions dialog)" ]; then
+      echo "dialog not installed.\nInstalling dialog from Homebrew..."
+      brew install dialog
+  fi
 
   if ! hash pip 2>/dev/null; then
-      echo "pip Not Installed\nInstalling python from Homebrew..."
+      echo "pip not installed.\nInstalling python from Homebrew..."
       brew install python
   fi
 
   if ! hash virtualenv 2>/dev/null; then
-      echo "virtualenv Not Installed\nInstalling with pip"
+      echo "virtualenv not installed.\nInstalling with pip..."
       pip install virtualenv
   fi
 }
diff --git a/letsencrypt-auto-source/pieces/bootstrappers/mac.sh b/letsencrypt-auto-source/pieces/bootstrappers/mac.sh
index 9318d18c8..23c12eec3 100755
--- a/letsencrypt-auto-source/pieces/bootstrappers/mac.sh
+++ b/letsencrypt-auto-source/pieces/bootstrappers/mac.sh
@@ -1,19 +1,26 @@
 BootstrapMac() {
   if ! hash brew 2>/dev/null; then
-      echo "Homebrew Not Installed\nDownloading..."
+      echo "Homebrew not installed.\nDownloading..."
       ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
   fi
 
-  brew install augeas
-  brew install dialog
+  if [ -z "$(brew list --versions augeas)" ]; then
+      echo "augeas not installed.\nInstalling augeas from Homebrew..."
+      brew install augeas
+  fi
+
+  if [ -z "$(brew list --versions dialog)" ]; then
+      echo "dialog not installed.\nInstalling dialog from Homebrew..."
+      brew install dialog
+  fi
 
   if ! hash pip 2>/dev/null; then
-      echo "pip Not Installed\nInstalling python from Homebrew..."
+      echo "pip not installed.\nInstalling python from Homebrew..."
       brew install python
   fi
 
   if ! hash virtualenv 2>/dev/null; then
-      echo "virtualenv Not Installed\nInstalling with pip"
+      echo "virtualenv not installed.\nInstalling with pip..."
       pip install virtualenv
   fi
 }