diff --git a/.changelog/24530.txt b/.changelog/24530.txt
new file mode 100644
index 00000000000..1eee2e0dd9b
--- /dev/null
+++ b/.changelog/24530.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+resource/aws_ssm_document: Always include `attachment_sources` when updating SSM documents
+```
diff --git a/internal/service/ssm/document.go b/internal/service/ssm/document.go
index ee3091e8f52..617a6d8e7bd 100644
--- a/internal/service/ssm/document.go
+++ b/internal/service/ssm/document.go
@@ -673,8 +673,8 @@ func updateDocument(d *schema.ResourceData, meta interface{}) error {
 		updateDocInput.VersionName = aws.String(v.(string))
 	}
 
-	if d.HasChange("attachments_source") {
-		updateDocInput.Attachments = expandSsmAttachmentsSources(d.Get("attachments_source").([]interface{}))
+	if v, ok := d.GetOk("attachments_source"); ok {
+		updateDocInput.Attachments = expandSsmAttachmentsSources(v.([]interface{}))
 	}
 
 	newDefaultVersion := d.Get("default_version").(string)