diff --git a/pyebsdindex/nlpar_cpu.py b/pyebsdindex/nlpar_cpu.py
index f9a2a1b..cf7e19c 100644
--- a/pyebsdindex/nlpar_cpu.py
+++ b/pyebsdindex/nlpar_cpu.py
@@ -326,6 +326,9 @@ def calcnlpar(self, chunksize=0, searchradius=None, lam = None, dthresh = None,
     sr = np.int64(self.searchradius)
     diff_offset = np.float32(self.diff_offset)
 
+    if type(diff_offset) is np.ndarray:
+      diff_offset = np.float32(diff_offset[0])
+
     if filename is not None:
       self.setfile(filepath=filename)