diff --git a/MagickCore/fx.c b/MagickCore/fx.c
index 981373f..afd3738 100644
--- a/MagickCore/fx.c
+++ b/MagickCore/fx.c
@@ -1175,7 +1175,7 @@
     (double) channel,symbol);
   value=(const char *) GetValueFromSplayTree(fx_info->symbols,key);
   if (value != (const char *) NULL)
-    return(QuantumScale*InterpretLocaleValue(value,(char **) NULL));
+    return(QuantumScale*StringToDouble(value,(char **) NULL));
   (void) DeleteNodeFromSplayTree(fx_info->symbols,key);
   if (LocaleNCompare(symbol,"depth",5) == 0)
     {
@@ -1242,7 +1242,7 @@
     }
   (void) AddValueToSplayTree(fx_info->symbols,ConstantString(key),
     ConstantString(statistic));
-  return(QuantumScale*InterpretLocaleValue(statistic,(char **) NULL));
+  return(QuantumScale*StringToDouble(statistic,(char **) NULL));
 }
 
 static MagickRealType
@@ -1835,7 +1835,7 @@
   }
   value=(const char *) GetValueFromSplayTree(fx_info->symbols,symbol);
   if (value != (const char *) NULL)
-    return((MagickRealType) InterpretLocaleValue(value,(char **) NULL));
+    return((MagickRealType) StringToDouble(value,(char **) NULL));
   (void) ThrowMagickException(exception,GetMagickModule(),OptionError,
     "UnableToParseExpression","`%s'",symbol);
   return(0.0);
@@ -2876,7 +2876,7 @@
       break;
   }
   q=(char *) expression;
-  alpha=InterpretLocaleValue(expression,&q);
+  alpha=InterpretSiPrefixValue(expression,&q);
   if (q == expression)
     return(FxGetSymbol(fx_info,channel,x,y,expression,exception));
   return(alpha);