diff --git a/router/java/src/net/i2p/router/tunnel/TunnelDispatcher.java b/router/java/src/net/i2p/router/tunnel/TunnelDispatcher.java
index 681dadec1..6b5457719 100644
--- a/router/java/src/net/i2p/router/tunnel/TunnelDispatcher.java
+++ b/router/java/src/net/i2p/router/tunnel/TunnelDispatcher.java
@@ -605,12 +605,17 @@ public class TunnelDispatcher implements Service {
         if (pctDrop <= 0)
             return false;
         // increase the drop probability for OBEP,
+        // (except lower it for tunnel build messages (type 21)),
         // and lower it for IBGW, for network efficiency
         double len = length;
-        if (type.startsWith("OBEP"))
-            len *= 1.5;
-        else if (type.startsWith("IBGW"))
+        if (type.startsWith("OBEP")) {
+            if (type.equals("OBEP 21"))
+                len /= 1.5;
+            else
+                len *= 1.5;
+        } else if (type.startsWith("IBGW")) {
             len /= 1.5;
+        }
         // drop in proportion to size w.r.t. a standard 1024-byte message
         // this is a little expensive but we want to adjust the curve between 0 and 1
         // Most messages are 1024, only at the OBEP do we see other sizes