diff --git a/roscopter/src/ekf/meas.cpp b/roscopter/src/ekf/meas.cpp
index c7992868..af2eb63a 100644
--- a/roscopter/src/ekf/meas.cpp
+++ b/roscopter/src/ekf/meas.cpp
@@ -34,6 +34,8 @@ std::string Base::Type() const
     case ZERO_VEL:
         return "ZeroVel";
         break;
+    default:
+        return "unknown";
     }
 }
 
diff --git a/roscopter/src/ekf/state.cpp b/roscopter/src/ekf/state.cpp
index d72d4760..c09270e1 100644
--- a/roscopter/src/ekf/state.cpp
+++ b/roscopter/src/ekf/state.cpp
@@ -172,7 +172,7 @@ State& State::operator+=(const VectorXd& dx)
     bb += dx(ErrorState::DBB);
     ref += dx(ErrorState::DREF);
 
-    *this;
+    return *this;
 }
 
 State& State::operator+=(const ErrorState& dx)