diff --git a/src/operator/image/image_random-inl.h b/src/operator/image/image_random-inl.h
index 42e4e9395a94..f37198fb0203 100644
--- a/src/operator/image/image_random-inl.h
+++ b/src/operator/image/image_random-inl.h
@@ -554,7 +554,7 @@ inline void RandomSaturation(const nnvm::NodeAttrs &attrs,
   AdjustSaturationImpl(alpha_s, ctx, inputs, req, outputs);
 }
 
-void RGB2HLSConvert(const float& src_r,
+inline void RGB2HLSConvert(const float& src_r,
                     const float& src_g,
                     const float& src_b,
                     float *dst_h,