diff --git a/src/org/rascalmpl/library/lang/json/internal/JsonValueWriter.java b/src/org/rascalmpl/library/lang/json/internal/JsonValueWriter.java
index e836f63576..68830ddf99 100644
--- a/src/org/rascalmpl/library/lang/json/internal/JsonValueWriter.java
+++ b/src/org/rascalmpl/library/lang/json/internal/JsonValueWriter.java
@@ -126,8 +126,8 @@ public Void visitReal(IReal o) throws IOException {
       @Override
       public Void visitRational(IRational o) throws IOException {
           out.beginArray();
-          out.value(o.numerator().getStringRepresentation());
-          out.value(o.denominator().getStringRepresentation());
+          out.value(o.numerator().longValue());
+          out.value(o.denominator().longValue());
           out.endArray();
 
           return null;
diff --git a/src/org/rascalmpl/library/lang/rascal/tests/library/lang/json/JSONIOTests.rsc b/src/org/rascalmpl/library/lang/rascal/tests/library/lang/json/JSONIOTests.rsc
index cbc86face5..8c4bebe763 100644
--- a/src/org/rascalmpl/library/lang/rascal/tests/library/lang/json/JSONIOTests.rsc
+++ b/src/org/rascalmpl/library/lang/rascal/tests/library/lang/json/JSONIOTests.rsc
@@ -8,6 +8,7 @@ import IO;
 import util::Math;
 import Type;
 import DateTime;
+import List;
 
 loc targetFile = |memory://test-tmp/test-<"<uuidi()>">.json|;
 
@@ -88,23 +89,26 @@ default value numNormalizer(value x) = x;
 
 
 @synopsis{Normalizer used to replace unrecoverable types with their default representatives}
-value toDefaultRec(value readBack) = visit(readBack) {
+value toDefaultRec(value readBack) =  visit(readBack) {
     case value x => toDefaultValue(x)
 };
 
-value toDefaultValue(rat r) = ["<numerator(r)>", "<denominator(r)>"];
-value toDefaultValue(set[value] x) =  [*x];
+// this list order depends on the hashcodes of the children
+// as the writer is top-down and this rewrite is bottom-up 
+// we end up with different lists sometimes (if the elements have been rewritten).
+value toDefaultValue(set[value] x) = [*x]; 
+
 value toDefaultValue(map[void,void] _) =   "object"();
 value toDefaultValue(<>) =   [];
-value toDefaultValue(<x>) =   [x];
-value toDefaultValue(<x,y>) =   [x,y];
-value toDefaultValue(<x,y,z>) =   [x,y,z];
-value toDefaultValue(<x,y,z,a>) =   [x,y,z,a];
-value toDefaultValue(<x,y,z,a,b>) =   [x,y,z,a,b];
-value toDefaultValue(<x,y,z,a,b,c>) =   [x,y,z,a,b,c];
-value toDefaultValue(<x,y,z,a,b,c,d>) =   [x,y,z,a,b,c,d];
-value toDefaultValue(<x,y,z,a,b,c,d,e>) =   [x,y,z,a,b,c,d,e];
-value toDefaultValue(<x,y,z,a,b,c,d,e,f>) =   [x,y,z,a,b,c,d,e,f];
+value toDefaultValue(<value x>) =   [x];
+value toDefaultValue(<value x,value y>) =   [x,y];
+value toDefaultValue(<value x,value y,value z>) =   [x,y,z];
+value toDefaultValue(<value x,value y,value z,value a>) =   [x,y,z,a];
+value toDefaultValue(<value x,value y,value z,value a,value b>) =   [x,y,z,a,b];
+value toDefaultValue(<value x,value y,value z,value a,value b,value c>) =   [x,y,z,a,b,c];
+value toDefaultValue(<value x,value y,value z,value a,value b,value c,value d>) =   [x,y,z,a,b,c,d];
+value toDefaultValue(<value x,value y,value z,value a,value b,value c,value d,value e>) =   [x,y,z,a,b,c,d,e];
+value toDefaultValue(<value x,value y,value z,value a,value b,value c,value d,value e,value f>) =   [x,y,z,a,b,c,d,e,f];
 value toDefaultValue(loc l) {
     // this simulates the simplications the writer applies
     if (!(l.offset?)) {
@@ -120,6 +124,7 @@ value toDefaultValue(loc l) {
     }
 }
 
+value toDefaultValue(rat r) = [numerator(r), denominator(r)];
 value toDefaultValue(datetime t) = printDateTime(t, "yyyy-MM-dd\'T\'HH:mm:ssZ");
 value toDefaultValue(real r) =   round(r) when r - round(r) == 0;
 default value toDefaultValue(value x) = x;