diff --git a/src/template/check_yaml.sql b/src/template/check_yaml.sql
index 7465292..6bf1e19 100644
--- a/src/template/check_yaml.sql
+++ b/src/template/check_yaml.sql
@@ -34,5 +34,5 @@ CREATE OR REPLACE FUNCTION
   COMMENT = 'Parses and validates a YAML string.'
 AS
 $$
-  TO_VARCHAR(CHECK_YAML_ARRAY(TO_BINARY(YAML_STRING, 'UTF-8')), 'UTF-8')
+CASE WHEN YAML_STRING IS NULL THEN NULL ELSE TO_VARCHAR(CHECK_YAML_ARRAY(TO_BINARY(YAML_STRING, 'UTF-8')), 'UTF-8') END
 $$
diff --git a/src/template/yaml_to_json_array.sql b/src/template/yaml_to_json_array.sql
index 31c5585..6fdffce 100644
--- a/src/template/yaml_to_json_array.sql
+++ b/src/template/yaml_to_json_array.sql
@@ -34,5 +34,5 @@ CREATE OR REPLACE FUNCTION
   COMMENT = 'Parses a YAML string into a semi-structured value.'
 AS
 $$
-  PARSE_JSON(TO_VARCHAR(YAML_TO_JSON_ARRAY(TO_BINARY(YAML_STRING, 'UTF-8')), 'UTF-8'))
+CASE WHEN YAML_STRING IS NULL THEN NULL ELSE PARSE_JSON(TO_VARCHAR(YAML_TO_JSON_ARRAY(TO_BINARY(YAML_STRING, 'UTF-8')), 'UTF-8')) END
 $$
diff --git a/src/template/yaml_to_json_string.sql b/src/template/yaml_to_json_string.sql
index dc03a45..92e6ff9 100644
--- a/src/template/yaml_to_json_string.sql
+++ b/src/template/yaml_to_json_string.sql
@@ -34,5 +34,5 @@ CREATE OR REPLACE FUNCTION
   COMMENT = 'Parses a YAML string into a semi-structured value.'
 AS
 $$
-  PARSE_JSON(YAML_TO_JSON_STRING(YAML_STRING))
+CASE WHEN YAML_STRING IS NULL THEN NULL ELSE PARSE_JSON(YAML_TO_JSON_STRING(YAML_STRING)) END
 $$