diff --git a/tapeserver/castor/tape/tapeserver/SCSI/Structures.hpp b/tapeserver/castor/tape/tapeserver/SCSI/Structures.hpp
index ab342c1805b5886ec48e3ba48147515d65b3e0d3..6a53ebcad85024485813504f38a7c8b421e3d693 100644
--- a/tapeserver/castor/tape/tapeserver/SCSI/Structures.hpp
+++ b/tapeserver/castor/tape/tapeserver/SCSI/Structures.hpp
@@ -1275,7 +1275,7 @@ namespace SCSI {
       unsigned char               :3;              // Reserved
 
       // bytes 22-28
-      unsigned char volumeLabel[7];                // Seven characters from left of Volume Label
+      char volumeLabel[7];                         // Seven characters from left of Volume Label
 
       // byte 29
       unsigned char physicalWrap;                  // Physical wrap of the current location. LSB reflects current physical direction:
@@ -1348,10 +1348,10 @@ namespace SCSI {
       unsigned char LPOSRegion;
 
       // bytes 70-85
-      unsigned char ERPSummaryInformation[16];
+      char ERPSummaryInformation[16];
 
       // bytes 86-95
-      unsigned char cartridgeSerialNumber[10];    // This is the value from the CRM right-justified, not the Barcode
+      char cartridgeSerialNumber[10];    // This is the value from the CRM right-justified, not the Barcode
     };
     
     namespace RAO {