diff --git a/pyproject.toml b/pyproject.toml
index cd61e93..68046db 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,7 +23,7 @@ dependencies = [
 
 [project.optional-dependencies]
 # Pulled in only if the consumer imports a0_plugin_testkit.real.fasta2a.
-fasta2a = ["fasta2a==0.5.0", "httpx>=0.27", "uvicorn>=0.30"]
+fasta2a = ["fasta2a==2.0.1", "httpx>=0.27", "uvicorn>=0.30"]
 # Reserved for a future playwright.A0Page helper.
 playwright = ["playwright>=1.40"]