diff --git a/modules/programs/powerline-go.nix b/modules/programs/powerline-go.nix
index e523526a8..1fd5268b3 100644
--- a/modules/programs/powerline-go.nix
+++ b/modules/programs/powerline-go.nix
@@ -165,7 +165,9 @@ in
       }
 
       if [ "$TERM" != "linux" ]; then
-        PROMPT_COMMAND="_update_ps1;$PROMPT_COMMAND"
+        if [[ ";''${PROMPT_COMMAND:-};" != *";_update_ps1;"* ]]; then
+          PROMPT_COMMAND="_update_ps1''${PROMPT_COMMAND:+;$PROMPT_COMMAND}"
+        fi
       fi
     '';
 
diff --git a/tests/modules/programs/powerline-go/bash.nix b/tests/modules/programs/powerline-go/bash.nix
index aead1a180..e7051829a 100644
--- a/tests/modules/programs/powerline-go/bash.nix
+++ b/tests/modules/programs/powerline-go/bash.nix
@@ -26,5 +26,8 @@
     assertFileContains \
       home-files/.bashrc \
       '/bin/powerline-go -error $old_exit_status -shell bash -modules nix-shell -newline -path-aliases \~/project/foo=prj-foo -ignore-repos /home/me/project1,/home/me/project2'
+    assertFileContains \
+      home-files/.bashrc \
+      'if [[ ";''${PROMPT_COMMAND:-};" != *";_update_ps1;"* ]]; then'
   '';
 }