diff --git a/model/converter/thrift/jaeger/sampling_from_domain.go b/model/converter/thrift/jaeger/sampling_from_domain.go
index 563e5416559..c776072cd19 100644
--- a/model/converter/thrift/jaeger/sampling_from_domain.go
+++ b/model/converter/thrift/jaeger/sampling_from_domain.go
@@ -67,11 +67,12 @@ func convertPerOperationFromDomain(s *api_v2.PerOperationSamplingStrategies) *sa
 		DefaultLowerBoundTracesPerSecond: s.GetDefaultLowerBoundTracesPerSecond(),
 		DefaultUpperBoundTracesPerSecond: &s.DefaultUpperBoundTracesPerSecond,
 	}
-	if s.GetPerOperationStrategies() != nil {
-		r.PerOperationStrategies = make([]*sampling.OperationSamplingStrategy, len(s.GetPerOperationStrategies()))
-		for i, k := range s.PerOperationStrategies {
-			r.PerOperationStrategies[i] = convertOperationFromDomain(k)
-		}
+
+	perOp := s.GetPerOperationStrategies()
+	// Default to empty array so that json.Marshal returns [] instead of null (Issue #3891).
+	r.PerOperationStrategies = make([]*sampling.OperationSamplingStrategy, len(perOp))
+	for i, k := range perOp {
+		r.PerOperationStrategies[i] = convertOperationFromDomain(k)
 	}
 	return r
 }
diff --git a/model/converter/thrift/jaeger/sampling_from_domain_test.go b/model/converter/thrift/jaeger/sampling_from_domain_test.go
index 804397da1d8..8bc2280d3c5 100644
--- a/model/converter/thrift/jaeger/sampling_from_domain_test.go
+++ b/model/converter/thrift/jaeger/sampling_from_domain_test.go
@@ -116,7 +116,13 @@ func TestConvertPerOperationStrategyFromDomain(t *testing.T) {
 				PerOperationStrategies: []*sampling.OperationSamplingStrategy{{Operation: "fao"}},
 			},
 		},
-		{},
+		{
+			in: &api_v2.PerOperationSamplingStrategies{DefaultSamplingProbability: 15.2, DefaultUpperBoundTracesPerSecond: a, DefaultLowerBoundTracesPerSecond: 2},
+			expected: &sampling.PerOperationSamplingStrategies{
+				DefaultSamplingProbability: 15.2, DefaultUpperBoundTracesPerSecond: &a, DefaultLowerBoundTracesPerSecond: 2,
+				PerOperationStrategies: []*sampling.OperationSamplingStrategy{},
+			},
+		},
 	}
 	for _, test := range tests {
 		o := convertPerOperationFromDomain(test.in)