diff --git a/psutil/_pslinux.py b/psutil/_pslinux.py
index 40132794b..bc6c7ff42 100644
--- a/psutil/_pslinux.py
+++ b/psutil/_pslinux.py
@@ -1038,9 +1038,9 @@ def ionice_set(self, ioclass, value):
                 value = 0
             else:
                 value = 0
-            if not 0 <= value <= 8:
+            if not 0 <= value <= 7:
                 raise ValueError(
-                    "value argument range expected is between 0 and 8")
+                    "value argument range expected is between 0 and 7")
             return cext.proc_ioprio_set(self.pid, ioclass, value)
 
     if HAS_PRLIMIT: