diff --git a/routing/probability_bimodal.go b/routing/probability_bimodal.go
index a5a8ba342..35d1f1073 100644
--- a/routing/probability_bimodal.go
+++ b/routing/probability_bimodal.go
@@ -500,24 +500,36 @@ func (p *BimodalEstimator) probabilityFormula(capacityMsat, successAmountMsat,
 		failAmount = capacity
 	}
 
-	// Mission control may have some outdated values, we correct them here.
-	// TODO(bitromortac): there may be better decisions to make in these
-	//  cases, e.g., resetting failAmount=cap and successAmount=0.
+	// Mission control may have some outdated values with regard to the
+	// current channel capacity between a node pair. This can happen in case
+	// a large parallel channel was closed or if a channel was downscaled
+	// and can lead to success and/or failure amounts to be out of the range
+	// [0, capacity]. We assume that the liquidity situation of the channel
+	// is similar as before due to flow bias.
 
-	// failAmount should be capacity at max.
-	if failAmount > capacity {
-		log.Debugf("Correcting failAmount %v to capacity %v",
-			failAmount, capacity)
+	// In case we have a large success we need to correct it to be in the
+	// valid range. We set the success amount close to the capacity, because
+	// we assume to still be able to send. Any possible failure (that must
+	// in this case be larger than the capacity) is corrected as well.
+	if successAmount >= capacity {
+		log.Debugf("Correcting success amount %s and failure amount "+
+			"%s to capacity %s", successAmountMsat,
+			failAmount, capacityMsat)
 
+		// We choose the success amount to be one less than the
+		// capacity, to both fit success and failure amounts into the
+		// capacity range in a consistent manner.
+		successAmount = capacity - 1
 		failAmount = capacity
 	}
 
-	// successAmount should be capacity at max.
-	if successAmount > capacity {
-		log.Debugf("Correcting successAmount %v to capacity %v",
-			successAmount, capacity)
+	// Having no or only a small success, but a large failure only needs
+	// adjustment of the failure amount.
+	if failAmount > capacity {
+		log.Debugf("Correcting failure amount %s to capacity %s",
+			failAmountMsat, capacityMsat)
 
-		successAmount = capacity
+		failAmount = capacity
 	}
 
 	// We cannot send more than the fail amount.
diff --git a/routing/probability_bimodal_test.go b/routing/probability_bimodal_test.go
index d31332739..57590a865 100644
--- a/routing/probability_bimodal_test.go
+++ b/routing/probability_bimodal_test.go
@@ -212,6 +212,26 @@ func TestSuccessProbability(t *testing.T) {
 			amount:              largeAmount,
 			expectedProbability: 0.5,
 		},
+		// Larger success and larger failure than the old capacity are
+		// rescaled to still give a very high success rate.
+		{
+			name:                "smaller cap, large success/fail",
+			capacity:            capacity,
+			failAmount:          2*capacity + 1,
+			successAmount:       2 * capacity,
+			amount:              largeAmount,
+			expectedProbability: 1.0,
+		},
+		// A lower success amount is not rescaled.
+		{
+			name:          "smaller cap, large fail",
+			capacity:      capacity,
+			successAmount: smallAmount / 2,
+			failAmount:    2 * capacity,
+			amount:        smallAmount,
+			// See "previous success, larger amount".
+			expectedProbability: 0.851,
+		},
 	}
 
 	estimator := BimodalEstimator{