diff --git a/Cantera/src/numerics/DAE_Solver.h b/Cantera/src/numerics/DAE_Solver.h
index cb37eee20..d87f3b9a8 100644
--- a/Cantera/src/numerics/DAE_Solver.h
+++ b/Cantera/src/numerics/DAE_Solver.h
@@ -151,7 +151,7 @@ namespace Cantera {
         /**
          * Take one internal step.
          */
-        virtual int step(doublereal tout) {
+        virtual doublereal step(doublereal tout) {
             warn("step"); return 0;
         }