diff --git a/.changeset/wild-tigers-swim.md b/.changeset/wild-tigers-swim.md
new file mode 100644
index 0000000..ab764bb
--- /dev/null
+++ b/.changeset/wild-tigers-swim.md
@@ -0,0 +1,5 @@
+---
+"create-better-t-stack": patch
+---
+
+add supabase flag validation
diff --git a/apps/cli/src/index.ts b/apps/cli/src/index.ts
index 1fe1853..a5d7837 100644
--- a/apps/cli/src/index.ts
+++ b/apps/cli/src/index.ts
@@ -736,6 +736,13 @@ function processAndValidateFlags(
 					);
 					process.exit(1);
 				}
+			} else if (dbSetup === "supabase") {
+				if (effectiveDatabase !== "postgres") {
+					consola.fatal(
+						`Supabase setup requires PostgreSQL. Cannot use --db-setup supabase with --database ${effectiveDatabase}.`,
+					);
+					process.exit(1);
+				}
 			} else if (dbSetup === "prisma-postgres") {
 				if (effectiveDatabase !== "postgres") {
 					consola.fatal(