diff --git a/oni/home/config/common.scm b/oni/home/config/common.scm
index 71747ad..df1ff49 100644
--- a/oni/home/config/common.scm
+++ b/oni/home/config/common.scm
@@ -109,7 +109,8 @@
                "}\n"
                "preexec_functions+=(horizontal-rule)\n"
                "precmd_functions+=(horizontal-rule)\n"
-               "PROMPT=\"%T \\$(spwd) %B%(?.%F{2}.%F{1}[%?])>%b%f \""))))))
+               "PROMPT=\"%T \\$(spwd) %B%(?.%F{2}.%F{1}[%?])>%b%f \"")
+              (local-file "zsh/guix-environment.zsh"))))))
 
 (define home-guile-service
   (service home-guile-service-type
diff --git a/oni/home/config/zsh/guix-environment.zsh b/oni/home/config/zsh/guix-environment.zsh
new file mode 100644
index 0000000..9adf39f
--- /dev/null
+++ b/oni/home/config/zsh/guix-environment.zsh
@@ -0,0 +1,3 @@
+if [ -n "$GUIX_ENVIRONMENT" ]; then
+    export PROMPT="[dev] $PROMPT"
+fi