diff --git a/gdal/swig/python/scripts/gdal_calc.py b/gdal/swig/python/scripts/gdal_calc.py
index 609ac499dacd..d052209237f0 100755
--- a/gdal/swig/python/scripts/gdal_calc.py
+++ b/gdal/swig/python/scripts/gdal_calc.py
@@ -327,6 +327,8 @@ def doit(opts, args):
                     myval = gdalnumeric.BandReadAsArray(myFiles[i].GetRasterBand(myBandNo),
                                                         xoff=myX, yoff=myY,
                                                         win_xsize=nXValid, win_ysize=nYValid)
+                    if myval is None:
+                        raise Exception('Input block reading failed')
 
                     # fill in nodata values
                     if myNDV[i] is not None:
@@ -355,7 +357,14 @@ def doit(opts, args):
 
                 # write data block to the output file
                 myOutB = myOut.GetRasterBand(bandNo)
-                gdalnumeric.BandWriteArray(myOutB, myResult, xoff=myX, yoff=myY)
+                if gdalnumeric.BandWriteArray(myOutB, myResult, xoff=myX, yoff=myY) != 0:
+                    raise Exception('Block writing failed')
+
+    gdal.ErrorReset()
+    myOut.FlushCache()
+    myOut = None
+    if gdal.GetLastErrorMsg() != '':
+        raise Exception('Dataset writing failed')
 
     if not opts.quiet:
         print("100 - Done")