diff --git a/src/shell/bash.rs b/src/shell/bash.rs
index ce13f6c..7fcc8d3 100644
--- a/src/shell/bash.rs
+++ b/src/shell/bash.rs
@@ -1,6 +1,6 @@
 use crate::version_file_strategy::VersionFileStrategy;
 
-use super::shell::Shell;
+use super::{shell::Shell, trap_add_script::TRAP_ADD};
 use indoc::{formatdoc, indoc};
 use std::path::Path;
 
@@ -55,34 +55,12 @@ impl Shell for Bash {
     fn delete_on_exit(&self, fnm_multishell: &Path) -> Option<String> {
         Some(indoc::formatdoc!(
             r#"
-    # appends a command to a trap
-    #
-    # - 1st arg:  code to add
-    # - remaining args:  names of traps to modify
-    #
-    trap_add() {{
-        trap_add_cmd=$1; shift || fatal "${{FUNCNAME}} usage error"
-        for trap_add_name in "$@"; do
-            trap -- "$(
-                # helper fn to get existing trap command from output
-                # of trap -p
-                extract_trap_cmd() {{ printf '%s\n' "$3"; }}
-                # print existing trap command with newline
-                eval "extract_trap_cmd $(trap -p "${{trap_add_name}}")"
-                # print the new trap command
-                printf '%s\n' "${{trap_add_cmd}}"
-            )" "${{trap_add_name}}" \
-                || fatal "unable to add to trap ${{trap_add_name}}"
-        done
-    }}
-    # set the trace attribute for the above function.  this is
-    # required to modify DEBUG or RETURN traps because functions don't
-    # inherit them unless the trace attribute is set
-    declare -f -t trap_add
+    {TRAP_ADD}
 
-    trap_add 'echo hi; rm "{fnm_multishell}"' EXIT
+    __fnm_trap_add__ 'rm "{fnm_multishell}"' EXIT
             "#,
-            fnm_multishell = fnm_multishell.display()
+            fnm_multishell = fnm_multishell.display(),
+            TRAP_ADD = TRAP_ADD
         ))
     }
 }
diff --git a/src/shell/mod.rs b/src/shell/mod.rs
index 4e27cd0..e74452f 100644
--- a/src/shell/mod.rs
+++ b/src/shell/mod.rs
@@ -7,6 +7,7 @@ mod zsh;
 
 #[allow(clippy::module_inception)]
 mod shell;
+mod trap_add_script;
 
 pub use bash::Bash;
 pub use fish::Fish;
diff --git a/src/shell/trap_add_script.rs b/src/shell/trap_add_script.rs
new file mode 100644
index 0000000..de38262
--- /dev/null
+++ b/src/shell/trap_add_script.rs
@@ -0,0 +1,31 @@
+// This code is based on Richard Hansen's answer on StackOverflow:
+// https://stackoverflow.com/a/7287873/1176984
+
+pub const TRAP_ADD: &'static str = indoc::indoc!(
+    r#"
+    # appends a command to a trap
+    #
+    # - 1st arg:  code to add
+    # - remaining args:  names of traps to modify
+    #
+    __fnm_trap_add__() {
+        __fnm_trap_add___cmd=$1; shift || fatal "${FUNCNAME} usage error"
+        for __fnm_trap_add___name in "$@"; do
+            trap -- "$(
+                # helper fn to get existing trap command from output
+                # of trap -p
+                extract_trap_cmd() { printf '%s\n' "$3"; }
+                # print existing trap command with newline
+                eval "extract_trap_cmd $(trap -p "${__fnm_trap_add___name}")"
+                # print the new trap command
+                printf '%s\n' "${__fnm_trap_add___cmd}"
+            )" "${__fnm_trap_add___name}" \
+                || fatal "unable to add to trap ${__fnm_trap_add___name}"
+        done
+    }
+    # set the trace attribute for the above function.  this is
+    # required to modify DEBUG or RETURN traps because functions don't
+    # inherit them unless the trace attribute is set
+    declare -f -t __fnm_trap_add__
+    "#
+);
diff --git a/src/shell/zsh.rs b/src/shell/zsh.rs
index 9bc13ce..91fcc6f 100644
--- a/src/shell/zsh.rs
+++ b/src/shell/zsh.rs
@@ -51,4 +51,15 @@ impl Shell for Zsh {
             autoload_hook = autoload_hook
         ))
     }
+
+    fn delete_on_exit(&self, fnm_multishell: &Path) -> Option<String> {
+        Some(indoc::formatdoc!(
+            r#"
+            {TRAP_ADD}
+            __fnm_trap_add__ 'rm "{fnm_multishell}"' EXIT
+            "#,
+            fnm_multishell = fnm_multishell.display(),
+            TRAP_ADD = super::trap_add_script::TRAP_ADD
+        ))
+    }
 }