diff --git a/modules/home-environment.nix b/modules/home-environment.nix
index a562047b0..514ff13a8 100644
--- a/modules/home-environment.nix
+++ b/modules/home-environment.nix
@@ -633,7 +633,7 @@ in
       destination = "/etc/profile.d/hm-session-vars.sh";
       text = ''
         # Only source this once.
-        if [ -n "$__HM_SESS_VARS_SOURCED" ]; then return; fi
+        if [ -n "''${__HM_SESS_VARS_SOURCED-}" ]; then return; fi
         export __HM_SESS_VARS_SOURCED=1
 
         ${config.lib.shell.exportAll cfg.sessionVariables}
@@ -793,6 +793,7 @@ in
 
           export PATH="${activationBinPaths}"
           ${config.lib.bash.initHomeManagerLib}
+          source ${config.home.sessionVariablesPackage}/etc/profile.d/hm-session-vars.sh
 
           # The driver version indicates the behavior expected by the caller of
           # this script.
diff --git a/tests/modules/home-environment/session-variables-expected.txt b/tests/modules/home-environment/session-variables-expected.txt
index a96f61956..cf8581e22 100644
--- a/tests/modules/home-environment/session-variables-expected.txt
+++ b/tests/modules/home-environment/session-variables-expected.txt
@@ -1,5 +1,5 @@
 # Only source this once.
-if [ -n "$__HM_SESS_VARS_SOURCED" ]; then return; fi
+if [ -n "${__HM_SESS_VARS_SOURCED-}" ]; then return; fi
 export __HM_SESS_VARS_SOURCED=1
 @exportLocaleVar@
 export V1="v1"
diff --git a/tests/modules/home-environment/session-variables.nix b/tests/modules/home-environment/session-variables.nix
index 2cd4d2301..35a3dc5e4 100644
--- a/tests/modules/home-environment/session-variables.nix
+++ b/tests/modules/home-environment/session-variables.nix
@@ -6,7 +6,7 @@ let
 
   linuxExpected = ''
     # Only source this once.
-    if [ -n "$__HM_SESS_VARS_SOURCED" ]; then return; fi
+    if [ -n "''${__HM_SESS_VARS_SOURCED-}" ]; then return; fi
     export __HM_SESS_VARS_SOURCED=1
 
     export LOCALE_ARCHIVE_2_27="${config.i18n.glibcLocales}/lib/locale/locale-archive"
@@ -21,7 +21,7 @@ let
 
   darwinExpected = ''
     # Only source this once.
-    if [ -n "$__HM_SESS_VARS_SOURCED" ]; then return; fi
+    if [ -n "''${__HM_SESS_VARS_SOURCED-}" ]; then return; fi
     export __HM_SESS_VARS_SOURCED=1
 
     export V1="v1"