diff --git a/vibrio/server.py b/vibrio/server.py
index ac3aef6..1110ffe 100644
--- a/vibrio/server.py
+++ b/vibrio/server.py
@@ -126,7 +126,9 @@ def stop(self) -> None:
             self.log = None
 
         if status != signal.SIGTERM:
-            raise SystemError("Could not cleanly shutdown server subprocess")
+            raise SystemError(
+                f"Could not cleanly shutdown server subprocess; received return code {status}"
+            )
 
 
 class ServerAsync(ServerBase):
@@ -192,4 +194,6 @@ async def stop(self) -> None:
             self.log = None
 
         if status != signal.SIGTERM:
-            raise SystemError("Could not cleanly shutdown server subprocess")
+            raise SystemError(
+                f"Could not cleanly shutdown server subprocess; received return code {status}"
+            )