diff --git a/nipype/interfaces/mrtrix3/utils.py b/nipype/interfaces/mrtrix3/utils.py
index f999db7001..77c3047f20 100644
--- a/nipype/interfaces/mrtrix3/utils.py
+++ b/nipype/interfaces/mrtrix3/utils.py
@@ -560,7 +560,7 @@ class MRConvertInputSpec(MRTrix3BaseInputSpec):
         desc="output image",
     )
     coord = traits.List(
-        traits.Float,
+        traits.Int,
         sep=" ",
         argstr="-coord %s",
         desc="extract data at the specified coordinates",