diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5adb01c..a5025e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Allow extra arguments to restic-backup with `$RESTIC_BACKUP_EXTRA_ARGS`.
 - Add `$RESTIC_VERBOSITY_LEVEL` for debugging.
+- Assertion on all needed envionment variables in the backup and check scripts.
 
 ### Changed
 - Align terminology used in README with the one used by B2 for credentials (keyId + applicationKey pair).
diff --git a/usr/local/sbin/restic_backup.sh b/usr/local/sbin/restic_backup.sh
index b4f19b3..59d16da 100644
--- a/usr/local/sbin/restic_backup.sh
+++ b/usr/local/sbin/restic_backup.sh
@@ -11,6 +11,27 @@
 # Exit on error, unset var, pipe failure
 set -euo pipefail
 
+
+# Assert that all needed environment variables are set.
+# TODO in future if this grows, move this to a restic_lib.sh
+assert_envvars() {
+	local varnames=($@)
+	for varname in "${varnames[@]}"; do
+		# Check if variable is set, then if it is not empty (need to do both as of `set -u`).
+		if [ -z ${!varname+x} ] || [ -z ${!varname} ] ; then
+			printf "%s must be set with a value for this script to work.\n\nDid you forget to source a /etc/restic/*.env profile in the current shell before executing this script?\n" $varname >&2
+			exit 1
+		fi
+	done
+}
+assert_envvars \
+	B2_ACCOUNT_ID B2_ACCOUNT_KEY B2_CONNECTIONS \
+	BACKUP_PATHS BACKUP_TAG \
+	RESTIC_BACKUP_EXCLUDE_FILE RESTIC_BACKUP_EXTRA_ARGS RESTIC_PASSWORD_FILE RESTIC_REPOSITORY RESTIC_VERBOSITY_LEVEL \
+	RETENTION_DAYS RETENTION_MONTHS RETENTION_WEEKS RETENTION_YEARS
+
+
+
 # Clean up lock if we are killed.
 # If killed by systemd, like $(systemctl stop restic), then it kills the whole cgroup and all it's subprocesses.
 # However if we kill this script ourselves, we need this trap that kills all subprocesses manually.
diff --git a/usr/local/sbin/restic_check.sh b/usr/local/sbin/restic_check.sh
index 019677c..238e76e 100644
--- a/usr/local/sbin/restic_check.sh
+++ b/usr/local/sbin/restic_check.sh
@@ -2,8 +2,23 @@
 # Check the backups made with restic to Backblaze B2 for errors.
 # See restic_backup.sh on how this script is run (as it's analogous for this script).
 
-# Exit on failure, pipe failure
-set -e -o pipefail
+# Exit on error, unset var, pipe failure
+set -euo pipefail
+
+# Assert that all needed environment variables are set.
+assert_envvars() {
+	local varnames=($@)
+	for varname in "${varnames[@]}"; do
+		# Check if variable is set, then if it is not empty (need to do both as of `set -u`).
+		if [ -z ${!varname+x} ] || [ -z ${!varname} ] ; then
+			printf "%s must be set with a value for this script to work.\n\nDid you forget to source a /etc/restic/*.env profile in the current shell before executing this script?\n" $varname >&2
+			exit 1
+		fi
+	done
+}
+assert_envvars \
+	B2_ACCOUNT_ID B2_ACCOUNT_KEY B2_CONNECTIONS \
+	RESTIC_PASSWORD_FILE RESTIC_REPOSITORY RESTIC_VERBOSITY_LEVEL
 
 # Clean up lock if we are killed.
 # If killed by systemd, like $(systemctl stop restic), then it kills the whole cgroup and all it's subprocesses.