diff --git a/bin/git-credential-keyring b/bin/git-credential-keyring
index 02a50d7..6a7f87d 100755
--- a/bin/git-credential-keyring
+++ b/bin/git-credential-keyring
@@ -15,7 +15,7 @@ end
 
 if action == "get" then
 	local command = string.format('secret-tool lookup application git username %s host %s', options.username, options.host, options.username, options.host)
-	local file = io.popen(command, "r")
+	local file = assert(io.popen(command, "r"))
 	local password = file:read("all")
 	if password~="" then
 		print("password="..password)
@@ -25,7 +25,7 @@ if action == "get" then
 	file:close()
 elseif action == "store" then
 	local command = string.format('secret-tool store --label="git %s@%s" application git username %s host %s', options.username, options.host, options.username, options.host)
-	local file = io.popen(command, "w")
+	local file = assert(io.popen(command, "w"))
 	file:write(options.password)
 	file:close()
 elseif action == "erase" then