diff --git a/tcl/memory.tcl b/tcl/memory.tcl
index 83c96d6c9..a7f5b9ac4 100644
--- a/tcl/memory.tcl
+++ b/tcl/memory.tcl
@@ -58,7 +58,7 @@ set ACCESS_WIDTH_ANY  [expr $ACCESS_WIDTH_8 + $ACCESS_WIDTH_16 + $ACCESS_WIDTH_3
 set UNKNOWN(0,ACCESS_WIDTH) $ACCESS_WIDTH_NONE
 
 proc iswithin { ADDRESS BASE LEN } {
-    return [expr ((($ADDRESS - $BASE) > 0) && (($ADDRESS - $BASE + $LEN) > 0))]
+    return [expr ((($ADDRESS - $BASE) > 0) && (($BASE + $LEN - $ADDRESS) > 0))]
 }
 
 proc address_info { ADDRESS } {