diff --git a/source/Debugger/Debug.cpp b/source/Debugger/Debug.cpp
index 851cf0bd..7bd5b506 100644
--- a/source/Debugger/Debug.cpp
+++ b/source/Debugger/Debug.cpp
@@ -484,13 +484,17 @@ bool _Bookmark_Del( const WORD nAddress )
 		{
 //			g_aBookmarks.at( iBookmark ) = NO_6502_TARGET;
 			g_aBookmarks[ iBookmark ].bSet = false;
+			g_nBookmarks--;
 			bDeleted = true;
 		}
 	}
 	return bDeleted;
 }
 
-bool Bookmark_Find( const WORD nAddress )
+// Returns:
+//     0   if address does not have a bookmark set
+//     N+1 if there is an existing bookmark that has this address
+int Bookmark_Find( const WORD nAddress )
 {
 	// Ugh, linear search
 //	int nSize = g_aBookmarks.size();
@@ -500,10 +504,10 @@ bool Bookmark_Find( const WORD nAddress )
 		if (g_aBookmarks[ iBookmark ].nAddress == nAddress)
 		{
 			if (g_aBookmarks[ iBookmark ].bSet)
-				return true;
+				return iBookmark + 1;
 		}
 	}
-	return false;
+	return 0;
 }
 
 
@@ -598,15 +602,26 @@ Update_t CmdBookmarkAdd (int nArgs )
 			ConsoleDisplayPush( sText );
 			return ConsoleUpdate();
 		}
-		
-		if ((iBookmark < MAX_BOOKMARKS) && (g_nBookmarks < MAX_BOOKMARKS))
+
+		// 2.9.0.16 Fixed: Replacing an existing bookmark incorrectly increased the total bookmark count.
+		int nOldBookmark = Bookmark_Find( nAddress );
+		if (nOldBookmark)
 		{
-			g_aBookmarks[iBookmark].bSet = true;
-			g_aBookmarks[iBookmark].nAddress = nAddress;
-			bAdded = true;
-			g_nBookmarks++;
-			iBookmark++;
+			_Bookmark_Del( nAddress );
 		}
+
+		// 2.9.0.17 Fixed: If all bookmarks were used then setting a new one wouldn't update an existing one to the new address.
+		if (g_aBookmarks[ iBookmark ].bSet)
+		{
+			g_aBookmarks[ iBookmark ].nAddress = nAddress;
+			bAdded = true;
+		}
+		else
+			if (g_nBookmarks < MAX_BOOKMARKS)
+			{
+				bAdded = _Bookmark_Add( iBookmark, nAddress );
+				iBookmark++;
+			}
 	}
 
 	if (!bAdded)
diff --git a/source/Debugger/Debug.h b/source/Debugger/Debug.h
index 70d1327b..91ac7d5c 100644
--- a/source/Debugger/Debug.h
+++ b/source/Debugger/Debug.h
@@ -135,7 +135,7 @@
 // Prototypes _______________________________________________________________
 
 // Bookmarks
-	bool Bookmark_Find( const WORD nAddress );
+	int Bookmark_Find( const WORD nAddress );
 
 // Breakpoints
 	int CheckBreakpointsIO ();