diff --git a/lib/bourne-shell.sh b/lib/bourne-shell.sh
index 0c1121a80..c45e2f88f 100644
--- a/lib/bourne-shell.sh
+++ b/lib/bourne-shell.sh
@@ -60,26 +60,21 @@ esac
 # enable color support of ls and also add handy aliases
 if [ -x /usr/bin/dircolors ]; then
   test -r ~/.dircolors && eval "$(dircolors -b ~/.dircolors)" || eval "$(dircolors -b)"
-  alias ls='ls --color=auto'
-  #alias dir='dir --color=auto'
-  #alias vdir='vdir --color=auto'
+  _omb_util_alias ls='ls --color=auto'
+  #_omb_util_alias ls='dir --color=auto'
+  #_omb_util_alias vdir='vdir --color=auto'
 
-  alias grep='grep --color=auto'
-  alias fgrep='fgrep --color=auto'
-  alias egrep='egrep --color=auto'
+  # Note: aliases "grep", "fgrep", and "egrep" are merged in lib/grep.sh
 fi
 
 # colored GCC warnings and errors
 #export GCC_COLORS='error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01'
 
-# some more ls aliases
-alias ll='ls -alF'
-alias la='ls -A'
-alias l='ls -CF'
+# ls aliases are moved to "lib/directories.sh"
 
 # Add an "alert" alias for long running commands.  Use like so:
 #   sleep 10; alert
-alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
+_omb_util_alias alert='notify-send --urgency=low -i "$([ $? = 0 ] && echo terminal || echo error)" "$(history|tail -n1|sed -e '\''s/^\s*[0-9]\+\s*//;s/[;&|]\s*alert$//'\'')"'
 
 # Alias definitions.
 # You may want to put all your additions into a separate file like
diff --git a/lib/directories.sh b/lib/directories.sh
index 54641176b..7be070247 100644
--- a/lib/directories.sh
+++ b/lib/directories.sh
@@ -1,30 +1,35 @@
 #! bash oh-my-bash.module
 # Common directories functions
-alias cd..='cd ../'                         # Go back 1 directory level (for fast typers)
-alias ..='cd ../'                           # Go back 1 directory level
-alias ...='cd ../../'                       # Go back 2 directory levels
-alias .3='cd ../../../'                     # Go back 3 directory levels
-alias .4='cd ../../../../'                  # Go back 4 directory levels
-alias .5='cd ../../../../../'               # Go back 5 directory levels
-alias .6='cd ../../../../../../'            # Go back 6 directory levels
+_omb_util_alias cd..='cd ../'                         # Go back 1 directory level (for fast typers)
+_omb_util_alias ..='cd ../'                           # Go back 1 directory level
+_omb_util_alias ...='cd ../../'                       # Go back 2 directory levels
+_omb_util_alias .3='cd ../../../'                     # Go back 3 directory levels
+_omb_util_alias .4='cd ../../../../'                  # Go back 4 directory levels
+_omb_util_alias .5='cd ../../../../../'               # Go back 5 directory levels
+_omb_util_alias .6='cd ../../../../../../'            # Go back 6 directory levels
 
-alias -- -='cd -'
-alias 1='cd -'
-alias 2='cd -2'
-alias 3='cd -3'
-alias 4='cd -4'
-alias 5='cd -5'
-alias 6='cd -6'
-alias 7='cd -7'
-alias 8='cd -8'
-alias 9='cd -9'
+_omb_util_alias -='cd -'
+_omb_util_alias 1='cd -'
+_omb_util_alias 2='cd -2'
+_omb_util_alias 3='cd -3'
+_omb_util_alias 4='cd -4'
+_omb_util_alias 5='cd -5'
+_omb_util_alias 6='cd -6'
+_omb_util_alias 7='cd -7'
+_omb_util_alias 8='cd -8'
+_omb_util_alias 9='cd -9'
 
-alias md='mkdir -p'
-alias rd='rmdir'
-alias d='dirs -v | head -10'
+_omb_util_alias md='mkdir -p'
+_omb_util_alias rd='rmdir'
+_omb_util_alias d='dirs -v | head -10'
 
 # List directory contents
-alias lsa='ls -lah'
-alias l='ls -lah'
-alias ll='ls -lh'
-alias la='ls -lAh'
+_omb_util_alias lsa='ls -lha'
+_omb_util_alias l='ls -lha'
+_omb_util_alias ll='ls -lh'
+_omb_util_alias la='ls -lhA'
+
+# From bourne-shell.sh (unused)
+#_omb_util_alias l='ls -CF'
+#_omb_util_alias ll='ls -laF'
+#_omb_util_alias la='ls -A'
diff --git a/lib/grep.sh b/lib/grep.sh
index a05ef2a9f..f551ac1b4 100644
--- a/lib/grep.sh
+++ b/lib/grep.sh
@@ -23,7 +23,9 @@ fi
 
 # export grep settings
 if ((${#_omb_grep_options[@]} > 0)); then
-  alias grep="grep ${_omb_grep_options[*]}"
+  _omb_util_alias grep="grep ${_omb_grep_options[*]}"
+  _omb_util_alias grep="fgrep ${_omb_grep_options[*]}"
+  _omb_util_alias grep="egrep ${_omb_grep_options[*]}"
 fi
 
 # clean up
diff --git a/lib/misc.sh b/lib/misc.sh
index f91e68f41..fb5782c66 100644
--- a/lib/misc.sh
+++ b/lib/misc.sh
@@ -7,14 +7,14 @@ env_default PAGER 'less'
 env_default LESS '-R'
 
 ## super user alias
-alias _='sudo'
-alias please='sudo'
+_omb_util_alias _='sudo'
+_omb_util_alias please='sudo'
 
 ## more intelligent acking for ubuntu users
 if which ack-grep &> /dev/null; then
-  alias afind='ack-grep -il'
+  _omb_util_alias afind='ack-grep -il'
 else
-  alias afind='ack -il'
+  _omb_util_alias afind='ack -il'
 fi
 
 # only define LC_CTYPE if undefined
diff --git a/lib/utils.sh b/lib/utils.sh
index 08233a73e..ae8623017 100644
--- a/lib/utils.sh
+++ b/lib/utils.sh
@@ -388,3 +388,15 @@ _omb_util_glob_expand() {
   [[ :$shopt: == *:failglob:* ]] && shopt -s failglob
   return 0
 }
+
+_omb_util_alias() {
+  case ${OMB_DEFAULT_ALIASES:-enable} in
+  (disable) return 0 ;;
+  (check) alias -- "${1%%=*}" &>/dev/null && return 0 ;;
+  (enable) ;;
+  (*)
+    _omb_log_error "invalid value: OMB_DEFAULT_ALIASES='${OMB_DEFAULT_ALIASES-}' (expect: enable|disable|check)" >&2
+    return 2
+  esac
+  alias -- "$1"
+}
diff --git a/templates/bashrc.osh-template b/templates/bashrc.osh-template
index 31ba8a1f3..bf3719588 100644
--- a/templates/bashrc.osh-template
+++ b/templates/bashrc.osh-template
@@ -46,6 +46,10 @@ OSH_THEME="font"
 # The optional three formats: "mm/dd/yyyy"|"dd.mm.yyyy"|"yyyy-mm-dd"
 # HIST_STAMPS="mm/dd/yyyy"
 
+# Uncomment the following line if you do not want OMB to overwrite the existing
+# aliases by the default OMB aliases defined in lib/*.sh
+# OMB_DEFAULT_ALIASES="check"
+
 # Would you like to use another custom folder than $OSH/custom?
 # OSH_CUSTOM=/path/to/new-custom-folder