--- a/ExternalLibraryFunction.st	Sat Jun 04 03:31:52 2016 +0200
+++ b/ExternalLibraryFunction.st	Sat Jun 04 04:06:22 2016 +0200
@@ -1068,7 +1068,7 @@
     int __returnType = 0;
     int thisType;
     int __callType = FFI_DEFAULT_ABI;
-
+    int __anyFloatOrDoubleArg = 0;
 #endif
 
     union u {
@@ -1528,7 +1528,6 @@
 		__FAIL__(@symbol(InvalidArgument))
 	    }
 	    argValuePtr = &(__argValues[i].fVal);
-
 	} else if (typeSymbol == @symbol(double)) {
 	    thisType = TYPE_DOUBLE;
 	    if (__isSmallInteger(arg)) {
@@ -1767,6 +1766,9 @@
 	__argTypes[i] = thisType;
 	__argValuePointers[i] = argValuePtr;
 
+	if ((thisType == TYPE_FLOAT) || (thisType == TYPE_DOUBLE)) {
+	    __anyFloatOrDoubleArg = 1;
+	}
 # ifdef VERBOSE
 	if (@global(Verbose) == true) {
 	    printf("arg%d: %"_lx_" type:%"_lx_"\n", i+1, (INT)(__argValues[i].iVal), (INT)thisType);
@@ -1861,6 +1863,18 @@
     // and the return types float and double are handled diferently from ints.
     // If that is not correct for your CPU/architecture, an ifndef is required here.
 
+#  if defined(__x86_64__)
+    if (__anyFloatOrDoubleArg) {
+#   ifdef VERBOSE
+	if (@global(Verbose) == true) {
+	    printf("float/double args currently not supported\n");
+	}
+#   endif
+	failureCode = @symbol(FFIDoubleArgNotSupported);
+	goto getOutOfHere;
+    }
+#  endif
+
 #  if !defined(SomeArchitechtureForWhichAboveIsNotTrue)
     {
 	VOIDPTRFUNC fi = (VOIDPTRFUNC)codeAddress;
@@ -1949,7 +1963,7 @@
 							 __argValues[12].pointerVal, __argValues[13].pointerVal, __argValues[14].pointerVal );
 			break;
 		    default:
-			failureCode = @symbol(FFINotSupported);
+			failureCode = @symbol(TooManyArguments);
 			goto getOutOfHere;
 		}
 		break;
@@ -2035,7 +2049,7 @@
 							 __argValues[12].pointerVal, __argValues[13].pointerVal, __argValues[14].pointerVal );
 			break;
 		    default:
-			failureCode = @symbol(FFINotSupported);
+			failureCode = @symbol(TooManyArguments);
 			goto getOutOfHere;
 		}
 	}