diff --git a/tmux/tmux/bash_history.sh b/tmux/tmux/bash_history.sh
index f927cd0..a08c568 100644
--- a/tmux/tmux/bash_history.sh
+++ b/tmux/tmux/bash_history.sh
@@ -8,4 +8,7 @@ HISTTIMEFORMAT="%F %T  "
 shopt -s histappend
 
 # After each command: flush to file, reload from file (syncs across all panes/windows)
-PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND; }history -a; history -c; history -r"
+# Guard against double-sourcing (e.g. multiple tmux panes all source ~/.bashrc)
+if [[ "$PROMPT_COMMAND" != *"history -a; history -c; history -r"* ]]; then
+    PROMPT_COMMAND="${PROMPT_COMMAND:+${PROMPT_COMMAND%;};} history -a; history -c; history -r"
+fi