diff --git a/mcfly.bash b/mcfly.bash
index 197fe170..561adcb6 100644
--- a/mcfly.bash
+++ b/mcfly.bash
@@ -59,7 +59,7 @@ function mcfly_prompt_command {
 # Set $PROMPT_COMMAND run mcfly_prompt_command and then any existing $PROMPT_COMMAND.
 PROMPT_COMMAND="mcfly_prompt_command;$PROMPT_COMMAND"
 
-# If this is an interactive shell, take ownership of ctrl-r.
+# If this is an interactive shell, take ownership of ctrl-r and set terminal color.
 if [[ $- =~ .*i.* ]]; then
   if [[ ${BASH_VERSINFO[0]} -ge 4 ]]; then
     # shellcheck disable=SC2016
@@ -78,4 +78,10 @@ if [[ $- =~ .*i.* ]]; then
       bind "'\C-r': '\C-amcfly: \e# mcfly search\C-m'"
     fi
   fi
+
+  if [[ "$COLORFGBG" =~ \;15$ ]]; then
+    export MCFLY_LIGHT=TRUE
+  elif [[ "$TERM_PROGRAM" == "Apple_Terminal" && $(defaults read -g AppleInterfaceStyle 2> /dev/null) != 'Dark' ]]; then
+    export MCFLY_LIGHT=TRUE
+  fi
 fi
diff --git a/mcfly.fish b/mcfly.fish
index cdbbfe2a..8c6a2264 100644
--- a/mcfly.fish
+++ b/mcfly.fish
@@ -42,7 +42,7 @@ function __mcfly_add_command -d 'Add run commands to McFly database' -e fish_pos
   eval $__MCFLY_CMD add --exit '$last_status' --old-dir '$__MCFLY_OLD_PWD' -- '$argv[1]'
 end
 
-# If this is an interactive shell, set up key binding functions.
+# If this is an interactive shell, set up key binding functions and terminal color.
 if status is-interactive
   function __mcfly-history-widget -d "Search command history with McFly"
     set -l mcfly_output (mktemp -t mcfly.output.XXXXXXXX)
@@ -67,11 +67,23 @@ if status is-interactive
   end
 
   function mcfly_key_bindings -d "Default key bindings for McFly"
-     bind \cr __mcfly-history-widget
-     if bind -M insert >/dev/null 2>&1
-       bind -M insert \cr __mcfly-history-widget
-     end
+    bind \cr __mcfly-history-widget
+    if bind -M insert >/dev/null 2>&1
+      bind -M insert \cr __mcfly-history-widget
+    end
+  end
+
+  function mcfly_detect_terminal_color -d 'Attempt to determine if running in light mode'
+    if string match -r '\;15$' $COLORFGBG &> /dev/null
+      set -gx MCFLY_LIGHT TRUE
+    else if test "$TERM_PROGRAM" = "Apple_Terminal"
+      set apple_interface (defaults read -g AppleInterfaceStyle 2> /dev/null)
+      if [ "$apple_interface" != 'Dark' ]
+        set -gx MCFLY_LIGHT TRUE
+      end
+    end
   end
 
   mcfly_key_bindings
+  mcfly_detect_terminal_color
 end
diff --git a/mcfly.zsh b/mcfly.zsh
index 9fda135d..fb3c6a2b 100644
--- a/mcfly.zsh
+++ b/mcfly.zsh
@@ -61,7 +61,7 @@ exit_logger() {
 }
 zshexit_functions+=(exit_logger)
 
-# If this is an interactive shell, take ownership of ctrl-r.
+# If this is an interactive shell, take ownership of ctrl-r and set terminal color.
 if [[ $- =~ .*i.* ]]; then
   mcfly-history-widget() {
     () {
@@ -90,4 +90,10 @@ if [[ $- =~ .*i.* ]]; then
   }
   zle -N mcfly-history-widget
   bindkey '^R' mcfly-history-widget
+
+  if [[ "$COLORFGBG" =~ \;15$ ]]; then
+    export MCFLY_LIGHT=TRUE
+  elif [[ "$TERM_PROGRAM" == "Apple_Terminal" && $(defaults read -g AppleInterfaceStyle 2> /dev/null) != 'Dark' ]]; then
+    export MCFLY_LIGHT=TRUE
+  fi
 fi