diff --git a/paddle/gserver/layers/DetectionOutputLayer.cpp b/paddle/gserver/layers/DetectionOutputLayer.cpp
index 8ab838e191314ab25469631626c0b0564d7fffda..a1036ea866beab53611d5a954708718fe2307326 100644
--- a/paddle/gserver/layers/DetectionOutputLayer.cpp
+++ b/paddle/gserver/layers/DetectionOutputLayer.cpp
@@ -139,6 +139,7 @@ void DetectionOutputLayer::forward(PassType passType) {
                                        allDecodedBBoxes,
                                        &allIndices);
 
+  numKept = numKept > 0 ? numKept : 1;
   resetOutput(numKept, 7);
   MatrixPtr outV = getOutputValue();
   getDetectionOutput(confBuffer_->getData(),
diff --git a/paddle/gserver/layers/DetectionUtil.cpp b/paddle/gserver/layers/DetectionUtil.cpp
index 3e61adc66e60c54250e4f323452aa13045310879..92c6193035300537e539f6ae12db6b69144bc565 100644
--- a/paddle/gserver/layers/DetectionUtil.cpp
+++ b/paddle/gserver/layers/DetectionUtil.cpp
@@ -469,7 +469,7 @@ size_t getDetectionIndices(
     const size_t numClasses,
     const size_t backgroundId,
     const size_t batchSize,
-    const size_t confThreshold,
+    const real confThreshold,
     const size_t nmsTopK,
     const real nmsThreshold,
     const size_t keepTopK,
@@ -536,6 +536,8 @@ void getDetectionOutput(const real* confData,
   MatrixPtr outBuffer;
   Matrix::resizeOrCreate(outBuffer, numKept, 7, false, false);
   real* bufferData = outBuffer->getData();
+  for (size_t i = 0; i < 7; i++)
+     bufferData[i] = -1;
   size_t count = 0;
   for (size_t n = 0; n < batchSize; ++n) {
     for (map<size_t, vector<size_t>>::const_iterator it = allIndices[n].begin();
diff --git a/paddle/gserver/layers/DetectionUtil.h b/paddle/gserver/layers/DetectionUtil.h
index fe4f9f075e4cf011c97f68f49598a828d62327b3..641ed873b4c8645b6455e5ef5e63593e3005b770 100644
--- a/paddle/gserver/layers/DetectionUtil.h
+++ b/paddle/gserver/layers/DetectionUtil.h
@@ -275,7 +275,7 @@ size_t getDetectionIndices(
     const size_t numClasses,
     const size_t backgroundId,
     const size_t batchSize,
-    const size_t confThreshold,
+    const real confThreshold,
     const size_t nmsTopK,
     const real nmsThreshold,
     const size_t keepTopK,