diff --git a/interfaces/matlab/toolbox/conhp.m b/interfaces/matlab/toolbox/conhp.m
index d5b5f5b7f..8789573bb 100755
--- a/interfaces/matlab/toolbox/conhp.m
+++ b/interfaces/matlab/toolbox/conhp.m
@@ -8,7 +8,8 @@ function dydt = conhp(t,y,gas,mw) %#ok<INUSL>
 
 
 % Set the state of the gas, based on the current solution vector.
-set(gas, 'T', y(1), 'P', pressure(gas), 'Y', y(2:end));
+setMassFractions(gas, y(2:end), 'nonorm');
+set(gas, 'T', y(1), 'P', pressure(gas));
 
 % energy equation
 wdot = netProdRates(gas);
diff --git a/interfaces/matlab/toolbox/conuv.m b/interfaces/matlab/toolbox/conuv.m
index 8b060881b..276f89e58 100755
--- a/interfaces/matlab/toolbox/conuv.m
+++ b/interfaces/matlab/toolbox/conuv.m
@@ -8,7 +8,8 @@ function dydt = conuv(t,y,gas,mw) %#ok<INUSL>
 
 
 % Set the state of the gas, based on the current solution vector.
-set(gas, 'T', y(1), 'Rho', density(gas), 'Y', y(2:end));
+setMassFractions(gas, y(2:end), 'nonorm');
+set(gas, 'T', y(1), 'Rho', density(gas));
 nsp = nSpecies(gas);
 
 % energy equation