diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9b7db7d..f37d225 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 * issue#710: Fixing Typo in thold_daemons.service File
 * issue#714: Increase the Name column to 255 characters
 * issue#719: Plugin Disabled due to mix of string and int
+* issue#814: Normalize nullable notification template text before replacement
 * issue: All Columns checkd on Thresholds page
 * issue: Special character previous value handling broken on data query indexes with special characters
 
diff --git a/README.md b/README.md
index 46310dc..4516eda 100644
--- a/README.md
+++ b/README.md
@@ -27,6 +27,8 @@ and become familiar with its settings.  From there, you can provide overall
 control of thold, and set defaults for things like Email bodies, weekend
 exemptions, alert log retention, logging, etc.
 
+An unset notification template field is treated as empty text.
+
 As with much of Cacti, settings should be documented in line with the actual
 setting.  If you find that any of these settings are ambiguous, please create a
 pull request with your proposed changes.
diff --git a/tests/Unit/TholdStrReplaceTest.php b/tests/Unit/TholdStrReplaceTest.php
index 69006c3..9e31619 100644
--- a/tests/Unit/TholdStrReplaceTest.php
+++ b/tests/Unit/TholdStrReplaceTest.php
@@ -91,4 +91,29 @@ public function testEveryOccurrenceIsReplaced(): void {
 	public function testSubjectWithoutTheTagIsUnchanged(): void {
 		$this->assertSame('no tags here', thold_str_replace('<X>', 5, 'no tags here'));
 	}
+
+	/**
+	 * @return void
+	 */
+	public function testNullableSubjectIsNormalizedAtTheBoundary(): void {
+		$deprecations = [];
+		set_error_handler(static function ($severity, $message) use (&$deprecations) {
+			if ($severity === E_DEPRECATED) {
+				$deprecations[] = $message;
+
+				return true;
+			}
+
+			return false;
+		});
+
+		try {
+			$this->assertSame('', thold_str_replace('<X>', 'value', null));
+			$this->assertSame('', thold_str_replace('<X>', null, null));
+		} finally {
+			restore_error_handler();
+		}
+
+		$this->assertSame([], $deprecations);
+	}
 }
diff --git a/thold_functions.php b/thold_functions.php
index f195d30..6ece0f7 100644
--- a/thold_functions.php
+++ b/thold_functions.php
@@ -8362,12 +8362,12 @@ function thold_get_cached_name(&$thold_data) {
  * blanking it produced alert bodies reading "Current value is " for exactly
  * the case an operator most needs to see.
  *
- * @param string $search  Tag to replace.
- * @param mixed  $replace Value to substitute.
- * @param string $subject Text containing the tag.
+ * @param string      $search  Tag to replace.
+ * @param mixed       $replace Value to substitute.
+ * @param string|null $subject Text containing the tag.
  */
-function thold_str_replace(string $search, $replace, string $subject): string {
-	return str_replace($search, $replace ?? '', $subject);
+function thold_str_replace(string $search, $replace, ?string $subject): string {
+	return str_replace($search, $replace ?? '', $subject ?? '');
 }
 
 function thold_template_import($xml_data) {