diff --git a/src/core/kernels/boundconds.cuh b/src/core/kernels/boundconds.cuh
index 1a01d1b..1120489 100644
--- a/src/core/kernels/boundconds.cuh
+++ b/src/core/kernels/boundconds.cuh
@@ -73,7 +73,7 @@ kernel_periodic_boundconds(const int3 start, const int3 end, AcReal* vtxbuf)
     vtxbuf[dst_idx]   = vtxbuf[src_idx];
 }
 
-void
+static void
 periodic_boundconds(const cudaStream_t stream, const int3& start, const int3& end, AcReal* vtxbuf)
 {
     const dim3 tpb(8, 2, 8);
diff --git a/src/core/kernels/reductions.cuh b/src/core/kernels/reductions.cuh
index 26697e0..e07d820 100644
--- a/src/core/kernels/reductions.cuh
+++ b/src/core/kernels/reductions.cuh
@@ -171,7 +171,7 @@ kernel_reduce_block(const __restrict__ AcReal* scratchpad, const int num_blocks,
     *result = res;
 }
 
-AcReal
+static AcReal
 reduce_scal(const cudaStream_t stream, const ReductionType rtype, const int3& start,
             const int3& end, const AcReal* vtxbuf, AcReal* scratchpad, AcReal* reduce_result)
 {
@@ -225,7 +225,7 @@ reduce_scal(const cudaStream_t stream, const ReductionType rtype, const int3& st
     return result;
 }
 
-AcReal
+static AcReal
 reduce_vec(const cudaStream_t stream, const ReductionType rtype, const int3& start, const int3& end,
            const AcReal* vtxbuf0, const AcReal* vtxbuf1, const AcReal* vtxbuf2, AcReal* scratchpad,
            AcReal* reduce_result)