diff --git a/ethkey/KeyAux.h b/ethkey/KeyAux.h
index 63066f132..0324bd08b 100644
--- a/ethkey/KeyAux.h
+++ b/ethkey/KeyAux.h
@@ -290,7 +290,7 @@ public:
 			if (h128 u = fromUUID(_signKey))
 				return Secret(secretStore().secret(u, [&](){ return getPassword("Enter password for key: "); }));
 			if (_signKey.substr(0, 6) == "brain#" && _signKey.find(":") != string::npos)
-				return KeyManager::subkey(KeyManager::brain(_signKey.substr(_signKey.find(":"))), stoul(_signKey.substr(6, _signKey.find(":" - 7))));
+				return KeyManager::subkey(KeyManager::brain(_signKey.substr(_signKey.find(":"))), stoul(_signKey.substr(6, _signKey.find(":") - 7)));
 			if (_signKey.substr(0, 6) == "brain:")
 				return KeyManager::brain(_signKey.substr(6));
 			if (_signKey == "brain")