diff --git a/hepdata_converter/writers/yoda_writer.py b/hepdata_converter/writers/yoda_writer.py
index 909a69e..d936851 100644
--- a/hepdata_converter/writers/yoda_writer.py
+++ b/hepdata_converter/writers/yoda_writer.py
@@ -153,7 +153,8 @@ def _create_estimate(self):
             if idx not in global_indices:
                 global_indices.append(idx)
                 # construct Estimate
-                rtn.bin(idx).setVal(self.yval[i])
+                y = abs(self.yval[i]) if math.isnan(self.yval[i]) else self.yval[i]
+                rtn.bin(idx).setVal(y)
                 self._set_error_breakdown(i, rtn.bin(idx))
         del global_indices
         return rtn