diff --git a/src/finam/data/tools/core.py b/src/finam/data/tools/core.py
index 525d56636dbe19659626c579fda45f3db1c8fcc6..b628ae6077700f514794b942ba03263e672b97a5 100644
--- a/src/finam/data/tools/core.py
+++ b/src/finam/data/tools/core.py
@@ -180,8 +180,8 @@ def _no_grid_shape_valid(data_shape, grid):
         return False
     dshp = np.array(data_shape)
     gshp = np.array(grid.data_shape)
-    check = gshp != -1
-    return np.all(dshp[check] == gshp[check])
+    fix_dims = gshp != -1
+    return np.all(dshp[fix_dims] == gshp[fix_dims])
 
 
 def has_time_axis(xdata, grid):