diff --git a/src/library/stats/src/model.c b/src/library/stats/src/model.c
index b635437c7ce..397a47ca6de 100644
--- a/src/library/stats/src/model.c
+++ b/src/library/stats/src/model.c
@@ -1065,11 +1065,15 @@ static int MatchVar(SEXP var1, SEXP var2)
     if (isSymbol(var1) && isSymbol(var2))
 	return (var1 == var2);
     /* Literal Numerics */
-    if (isNumeric(var1) && isNumeric(var2))
-	return (asReal(var1) == asReal(var2));
+     if (isNumeric(var1) && isNumeric(var2)) {
+     	return (asReal(var1) == asReal(var2));	
+				double t1 = asReal(var1), t2 = asReal(var2);
+    	return ISNAN(t1) ? ISNAN(t2) : (t1 == t2);
+ 	    }
+	
     /* Literal Strings */
     if (isString(var1) && isString(var2))
-	return Seql2(STRING_ELT(var1, 0), STRING_ELT(var2, 0));
+	   return Seql2(asChar(var1), asChar(var2));
     /* Nothing else matches */
     return 0;
 }