diff --git a/src/clib/ct.cpp b/src/clib/ct.cpp
index 59456a5e4..cb6d965d9 100644
--- a/src/clib/ct.cpp
+++ b/src/clib/ct.cpp
@@ -222,8 +222,7 @@ extern "C" {
     {
         try {
             ThermoPhase& p = ThermoCabinet::item(n);
-            compositionMap xx = parseCompString(x, p.speciesNames());
-            p.setMoleFractionsByName(xx);
+            p.setMoleFractionsByName(x);
             return 0;
         } catch (...) {
             return handleAllExceptions(-1, ERR);
@@ -251,8 +250,7 @@ extern "C" {
     {
         try {
             ThermoPhase& p = ThermoCabinet::item(n);
-            compositionMap yy = parseCompString(y, p.speciesNames());
-            p.setMassFractionsByName(yy);
+            p.setMassFractionsByName(y);
             return 0;
         } catch (...) {
             return handleAllExceptions(-1, ERR);
diff --git a/src/fortran/fct.cpp b/src/fortran/fct.cpp
index 229d6453e..d0672ace2 100644
--- a/src/fortran/fct.cpp
+++ b/src/fortran/fct.cpp
@@ -251,8 +251,7 @@ extern "C" {
     {
         try {
             ThermoPhase* p = _fph(n);
-            compositionMap xx = parseCompString(f2string(x, lx), p->speciesNames());
-            p->setMoleFractionsByName(xx);
+            p->setMoleFractionsByName(f2string(x, lx));
         } catch (...) {
             return handleAllExceptions(-1, ERR);
         }
@@ -278,8 +277,7 @@ extern "C" {
     {
         try {
             ThermoPhase* p = _fph(n);
-            compositionMap yy = parseCompString(f2string(y, leny), p->speciesNames());
-            p->setMassFractionsByName(yy);
+            p->setMassFractionsByName(f2string(y, leny));
         } catch (...) {
             return handleAllExceptions(-1, ERR);
         }
diff --git a/src/thermo/ThermoPhase.cpp b/src/thermo/ThermoPhase.cpp
index b6dd71083..deca79b55 100644
--- a/src/thermo/ThermoPhase.cpp
+++ b/src/thermo/ThermoPhase.cpp
@@ -147,8 +147,7 @@ void ThermoPhase::setState_TPX(doublereal t, doublereal p, const compositionMap&
 
 void ThermoPhase::setState_TPX(doublereal t, doublereal p, const std::string& x)
 {
-    compositionMap xx = parseCompString(x, speciesNames());
-    setMoleFractionsByName(xx);
+    setMoleFractionsByName(x);
     setState_TP(t,p);
 }
 
@@ -166,8 +165,7 @@ void ThermoPhase::setState_TPY(doublereal t, doublereal p, const compositionMap&
 
 void ThermoPhase::setState_TPY(doublereal t, doublereal p, const std::string& y)
 {
-    compositionMap yy = parseCompString(y, speciesNames());
-    setMassFractionsByName(yy);
+    setMassFractionsByName(y);
     setState_TP(t,p);
 }