diff --git a/ompi/mca/bcol/basesmuma/bcol_basesmuma_buf_mgmt.c b/ompi/mca/bcol/basesmuma/bcol_basesmuma_buf_mgmt.c
index 1a65b5cb01..86a2811b00 100644
--- a/ompi/mca/bcol/basesmuma/bcol_basesmuma_buf_mgmt.c
+++ b/ompi/mca/bcol/basesmuma/bcol_basesmuma_buf_mgmt.c
@@ -99,6 +99,7 @@ int bcol_basesmuma_free_buff( sm_buffer_mgmt * buff_block,
      *   associated with this bank have been freed.
      */
     assert(generation == buff_block->ctl_buffs_mgmt[memory_bank].bank_gen_counter);
+    (void)generation;  // silence compiler warning
 
     /*
      * increment counter of completed buffers
diff --git a/ompi/mca/bcol/ptpcoll/bcol_ptpcoll_allreduce.c b/ompi/mca/bcol/ptpcoll/bcol_ptpcoll_allreduce.c
index 200e109f71..14a4f76958 100644
--- a/ompi/mca/bcol/ptpcoll/bcol_ptpcoll_allreduce.c
+++ b/ompi/mca/bcol/ptpcoll/bcol_ptpcoll_allreduce.c
@@ -255,6 +255,9 @@ int bcol_ptpcoll_allreduce_narraying_init(bcol_function_args_t *input_args,
     buffer_size  = ptpcoll_module->ml_mem.size_buffer - BCOL_HEADER_MAX;
     assert(buffer_size >= count * dtype->super.size *
            ptpcoll_module->k_nomial_radix);
+    (void)buffer_size;  // silence compiler warning
+    (void)dtype;
+    (void)count;
 
     return bcol_ptpcoll_allreduce_narraying_progress (input_args, const_args);
 }
diff --git a/ompi/mca/coll/base/coll_base_allgather.c b/ompi/mca/coll/base/coll_base_allgather.c
index 460a7861e5..d789edd89a 100644
--- a/ompi/mca/coll/base/coll_base_allgather.c
+++ b/ompi/mca/coll/base/coll_base_allgather.c
@@ -203,6 +203,7 @@ int ompi_coll_base_allgather_intra_bruck(const void *sbuf, int scount,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,  "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -339,6 +340,7 @@ ompi_coll_base_allgather_intra_recursivedoubling(const void *sbuf, int scount,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,  "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -426,6 +428,7 @@ int ompi_coll_base_allgather_intra_ring(const void *sbuf, int scount,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,  "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -599,6 +602,7 @@ ompi_coll_base_allgather_intra_neighborexchange(const void *sbuf, int scount,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,  "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -658,6 +662,7 @@ int ompi_coll_base_allgather_intra_two_procs(const void *sbuf, int scount,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
diff --git a/ompi/mca/coll/base/coll_base_allgatherv.c b/ompi/mca/coll/base/coll_base_allgatherv.c
index fc1df369d7..9b5cff2cbe 100644
--- a/ompi/mca/coll/base/coll_base_allgatherv.c
+++ b/ompi/mca/coll/base/coll_base_allgatherv.c
@@ -211,6 +211,7 @@ int ompi_coll_base_allgatherv_intra_bruck(const void *sbuf, int scount,
 
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,  "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -297,6 +298,7 @@ int ompi_coll_base_allgatherv_intra_ring(const void *sbuf, int scount,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,  "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -502,6 +504,7 @@ ompi_coll_base_allgatherv_intra_neighborexchange(const void *sbuf, int scount,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,  "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -563,6 +566,7 @@ int ompi_coll_base_allgatherv_intra_two_procs(const void *sbuf, int scount,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
diff --git a/ompi/mca/coll/base/coll_base_allreduce.c b/ompi/mca/coll/base/coll_base_allreduce.c
index 0c3ec93578..c21676af1e 100644
--- a/ompi/mca/coll/base/coll_base_allreduce.c
+++ b/ompi/mca/coll/base/coll_base_allreduce.c
@@ -269,6 +269,7 @@ ompi_coll_base_allreduce_intra_recursivedoubling(const void *sbuf, void *rbuf,
  error_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tRank %d Error occurred %d\n",
                  __FILE__, line, rank, ret));
+    (void)line;  // silence compiler warning
     if (NULL != inplacebuf) free(inplacebuf);
     return ret;
 }
@@ -528,6 +529,7 @@ ompi_coll_base_allreduce_intra_ring(const void *sbuf, void *rbuf, int count,
  error_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tRank %d Error occurred %d\n",
                  __FILE__, line, rank, ret));
+    (void)line;  // silence compiler warning
     if (NULL != inbuf[0]) free(inbuf[0]);
     if (NULL != inbuf[1]) free(inbuf[1]);
     return ret;
@@ -846,6 +848,7 @@ ompi_coll_base_allreduce_intra_ring_segmented(const void *sbuf, void *rbuf, int
  error_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tRank %d Error occurred %d\n",
                  __FILE__, line, rank, ret));
+    (void)line;  // silence compiler warning
     if (NULL != inbuf[0]) free(inbuf[0]);
     if (NULL != inbuf[1]) free(inbuf[1]);
     return ret;
diff --git a/ompi/mca/coll/base/coll_base_alltoall.c b/ompi/mca/coll/base/coll_base_alltoall.c
index 289296b5b3..c9a34b5fd0 100644
--- a/ompi/mca/coll/base/coll_base_alltoall.c
+++ b/ompi/mca/coll/base/coll_base_alltoall.c
@@ -124,6 +124,7 @@ mca_coll_base_alltoall_intra_basic_inplace(const void *rbuf, int rcount,
         OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
                      "%s:%4d\tError occurred %d, rank %2d", __FILE__, line, err,
                      rank));
+        (void)line;  // silence compiler warning
         ompi_coll_base_free_reqs(base_module->base_data->mcct_reqs, 2);
     }
 
@@ -185,6 +186,7 @@ int ompi_coll_base_alltoall_intra_pairwise(const void *sbuf, int scount,
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
                  "%s:%4d\tError occurred %d, rank %2d", __FILE__, line,
                  err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -307,6 +309,7 @@ int ompi_coll_base_alltoall_intra_bruck(const void *sbuf, int scount,
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
                  "%s:%4d\tError occurred %d, rank %2d", __FILE__, line, err,
                  rank));
+    (void)line;  // silence compiler warning
     if (tmpbuf != NULL) free(tmpbuf_free);
     if (displs != NULL) free(displs);
     if (blen != NULL) free(blen);
@@ -468,6 +471,7 @@ int ompi_coll_base_alltoall_intra_linear_sync(const void *sbuf, int scount,
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
                  "%s:%4d\tError occurred %d, rank %2d", __FILE__, line, error,
                  rank));
+    (void)line;  // silence compiler warning
     ompi_coll_base_free_reqs(reqs, 2 * total_reqs);
     return error;
 }
@@ -528,6 +532,7 @@ int ompi_coll_base_alltoall_intra_two_procs(const void *sbuf, int scount,
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
                  "%s:%4d\tError occurred %d, rank %2d", __FILE__, line, err,
                  rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -650,6 +655,7 @@ int ompi_coll_base_alltoall_intra_basic_linear(const void *sbuf, int scount,
     if( MPI_SUCCESS != err ) {
         OPAL_OUTPUT( (ompi_coll_base_framework.framework_output,"%s:%4d\tError occurred %d, rank %2d",
                       __FILE__, line, err, rank) );
+        (void)line;  // silence compiler warning
     }
     /* Free the reqs in all cases as they are persistent requests */
     ompi_coll_base_free_reqs(req, nreqs);
diff --git a/ompi/mca/coll/base/coll_base_alltoallv.c b/ompi/mca/coll/base/coll_base_alltoallv.c
index 97283d48ac..09da2593e0 100644
--- a/ompi/mca/coll/base/coll_base_alltoallv.c
+++ b/ompi/mca/coll/base/coll_base_alltoallv.c
@@ -47,7 +47,7 @@ mca_coll_base_alltoallv_intra_basic_inplace(const void *rbuf, const int *rcounts
     MPI_Request *preq;
     char *tmp_buffer;
     size_t max_size, rdtype_size;
-    OPAL_PTRDIFF_TYPE ext, gap;
+    OPAL_PTRDIFF_TYPE ext, gap = 0;
 
     /* Initialize. */
 
@@ -184,6 +184,7 @@ ompi_coll_base_alltoallv_intra_pairwise(const void *sbuf, const int *scounts, co
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,
                  "%s:%4d\tError occurred %d, rank %2d at step %d", __FILE__, line,
                  err, rank, step));
+    (void)line;  // silence compiler warning
     return err;
 }
 
diff --git a/ompi/mca/coll/base/coll_base_barrier.c b/ompi/mca/coll/base/coll_base_barrier.c
index 7aafd8d6a6..3ce5102c09 100644
--- a/ompi/mca/coll/base/coll_base_barrier.c
+++ b/ompi/mca/coll/base/coll_base_barrier.c
@@ -86,6 +86,7 @@ ompi_coll_base_sendrecv_zero(int dest, int stag,
      */
     OPAL_OUTPUT ((ompi_coll_base_framework.framework_output, "%s:%d: Error %d occurred\n",
                   __FILE__, line, err));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -169,6 +170,7 @@ int ompi_coll_base_barrier_intra_doublering(struct ompi_communicator_t *comm,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,"%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -247,6 +249,7 @@ int ompi_coll_base_barrier_intra_recursivedoubling(struct ompi_communicator_t *c
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,"%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -282,6 +285,7 @@ int ompi_coll_base_barrier_intra_bruck(struct ompi_communicator_t *comm,
  err_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,"%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -369,6 +373,7 @@ int ompi_coll_base_barrier_intra_basic_linear(struct ompi_communicator_t *comm,
  err_hndl:
     OPAL_OUTPUT( (ompi_coll_base_framework.framework_output,"%s:%4d\tError occurred %d, rank %2d",
                   __FILE__, line, err, rank) );
+    (void)line;  // silence compiler warning
     if( NULL != requests )
         ompi_coll_base_free_reqs(requests, size-1);
     return err;
diff --git a/ompi/mca/coll/base/coll_base_bcast.c b/ompi/mca/coll/base/coll_base_bcast.c
index 258832d128..bb051861ca 100644
--- a/ompi/mca/coll/base/coll_base_bcast.c
+++ b/ompi/mca/coll/base/coll_base_bcast.c
@@ -41,7 +41,7 @@ ompi_coll_base_bcast_intra_generic( void* buffer,
                                      uint32_t count_by_segment,
                                      ompi_coll_tree_t* tree )
 {
-    int err = 0, line, i, rank, size, segindex, req_index;
+    int err = 0, line, i, rank, segindex, req_index;
     int num_segments; /* Number of segments */
     int sendcount;    /* number of elements sent in this segment */
     size_t realsegsize, type_size;
@@ -52,9 +52,12 @@ ompi_coll_base_bcast_intra_generic( void* buffer,
     ompi_request_t **send_reqs = NULL;
 #endif
 
+#if OPAL_ENABLE_DEBUG
+    int size;
     size = ompi_comm_size(comm);
-    rank = ompi_comm_rank(comm);
     assert( size > 1 );
+#endif
+    rank = ompi_comm_rank(comm);
 
     ompi_datatype_get_extent (datatype, &lb, &extent);
     ompi_datatype_type_size( datatype, &type_size );
@@ -240,6 +243,7 @@ ompi_coll_base_bcast_intra_generic( void* buffer,
  error_hndl:
     OPAL_OUTPUT( (ompi_coll_base_framework.framework_output,"%s:%4d\tError occurred %d, rank %2d",
                   __FILE__, line, err, rank) );
+    (void)line;  // silence compiler warnings
     if( MPI_SUCCESS != err ) {
         ompi_coll_base_free_reqs( recv_reqs, 2);
         if( NULL != send_reqs ) {
@@ -603,6 +607,7 @@ ompi_coll_base_bcast_intra_split_bintree ( void* buffer,
 
  error_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,"%s:%4d\tError occurred %d, rank %2d", __FILE__,line,err,rank));
+    (void)line;  // silence compiler warning
     return (err);
 }
 
diff --git a/ompi/mca/coll/base/coll_base_gather.c b/ompi/mca/coll/base/coll_base_gather.c
index df14cee120..794b82bd6a 100644
--- a/ompi/mca/coll/base/coll_base_gather.c
+++ b/ompi/mca/coll/base/coll_base_gather.c
@@ -193,6 +193,7 @@ ompi_coll_base_gather_intra_binomial(const void *sbuf, int scount,
 
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,  "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
@@ -330,6 +331,7 @@ ompi_coll_base_gather_intra_linear_sync(const void *sbuf, int scount,
     OPAL_OUTPUT (( ompi_coll_base_framework.framework_output,
                    "ERROR_HNDL: node %d file %s line %d error %d\n",
                    rank, __FILE__, line, ret ));
+    (void)line;  // silence compiler warning
     return ret;
 }
 
diff --git a/ompi/mca/coll/base/coll_base_reduce.c b/ompi/mca/coll/base/coll_base_reduce.c
index c6a50e906c..f5b2449727 100644
--- a/ompi/mca/coll/base/coll_base_reduce.c
+++ b/ompi/mca/coll/base/coll_base_reduce.c
@@ -326,6 +326,7 @@ int ompi_coll_base_reduce_generic( const void* sendbuf, void* recvbuf, int origi
     OPAL_OUTPUT (( ompi_coll_base_framework.framework_output,
                    "ERROR_HNDL: node %d file %s line %d error %d\n",
                    rank, __FILE__, line, ret ));
+    (void)line;  // silence compiler warning
     if( inbuf_free[0] != NULL ) free(inbuf_free[0]);
     if( inbuf_free[1] != NULL ) free(inbuf_free[1]);
     if( accumbuf_free != NULL ) free(accumbuf);
diff --git a/ompi/mca/coll/base/coll_base_reduce_scatter.c b/ompi/mca/coll/base/coll_base_reduce_scatter.c
index d4c88e25f8..9bbd11455c 100644
--- a/ompi/mca/coll/base/coll_base_reduce_scatter.c
+++ b/ompi/mca/coll/base/coll_base_reduce_scatter.c
@@ -607,6 +607,7 @@ ompi_coll_base_reduce_scatter_intra_ring( const void *sbuf, void *rbuf, const in
  error_hndl:
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output, "%s:%4d\tRank %d Error occurred %d\n",
                  __FILE__, line, rank, ret));
+    (void)line;  // silence compiler warning
     if (NULL != displs) free(displs);
     if (NULL != accumbuf_free) free(accumbuf_free);
     if (NULL != inbuf_free[0]) free(inbuf_free[0]);
diff --git a/ompi/mca/coll/base/coll_base_scatter.c b/ompi/mca/coll/base/coll_base_scatter.c
index 21a4d8c9fa..44b09d28b9 100644
--- a/ompi/mca/coll/base/coll_base_scatter.c
+++ b/ompi/mca/coll/base/coll_base_scatter.c
@@ -170,6 +170,7 @@ ompi_coll_base_scatter_intra_binomial( const void *sbuf, int scount,
 
     OPAL_OUTPUT((ompi_coll_base_framework.framework_output,  "%s:%4d\tError occurred %d, rank %2d",
                  __FILE__, line, err, rank));
+    (void)line;  // silence compiler warning
     return err;
 }
 
diff --git a/ompi/mca/coll/base/coll_base_util.c b/ompi/mca/coll/base/coll_base_util.c
index e0e6a29a5e..a4e8c57cb8 100644
--- a/ompi/mca/coll/base/coll_base_util.c
+++ b/ompi/mca/coll/base/coll_base_util.c
@@ -100,6 +100,7 @@ int ompi_coll_base_sendrecv_nonzero_actual( void* sendbuf, size_t scount,
      */
     OPAL_OUTPUT ((ompi_coll_base_framework.framework_output, "%s:%d: Error %d occurred\n",
                   __FILE__, line, err));
+    (void)line;  // silence compiler warning
     if (MPI_STATUS_IGNORE != status) {
         status->MPI_ERROR = err;
     }
diff --git a/ompi/mca/coll/basic/coll_basic_allgather.c b/ompi/mca/coll/basic/coll_basic_allgather.c
index 7117735570..75870d2cfc 100644
--- a/ompi/mca/coll/basic/coll_basic_allgather.c
+++ b/ompi/mca/coll/basic/coll_basic_allgather.c
@@ -155,6 +155,7 @@ mca_coll_basic_allgather_inter(const void *sbuf, int scount,
     if( MPI_SUCCESS != err ) {
         OPAL_OUTPUT( (ompi_coll_base_framework.framework_output,"%s:%4d\tError occurred %d, rank %2d",
                       __FILE__, line, err, rank) );
+        (void)line;  // silence compiler warning
         if( NULL != reqs ) ompi_coll_base_free_reqs(reqs, rsize+1);
     }
     if (NULL != tmpbuf) {
diff --git a/ompi/mca/coll/basic/coll_basic_allreduce.c b/ompi/mca/coll/basic/coll_basic_allreduce.c
index c436556b19..e64094d02b 100644
--- a/ompi/mca/coll/basic/coll_basic_allreduce.c
+++ b/ompi/mca/coll/basic/coll_basic_allreduce.c
@@ -195,6 +195,7 @@ mca_coll_basic_allreduce_inter(const void *sbuf, void *rbuf, int count,
     if( MPI_SUCCESS != err ) {
         OPAL_OUTPUT((ompi_coll_base_framework.framework_output,"%s:%4d\tError occurred %d, rank %2d", __FILE__,
                      line, err, rank));
+        (void)line;  // silence compiler warning
         ompi_coll_base_free_reqs(reqs, rsize - 1);
     }
     if (NULL != tmpbuf) {
diff --git a/ompi/mca/coll/libnbc/nbc.c b/ompi/mca/coll/libnbc/nbc.c
index 81bb727501..ef9ace0ec4 100644
--- a/ompi/mca/coll/libnbc/nbc.c
+++ b/ompi/mca/coll/libnbc/nbc.c
@@ -294,7 +294,7 @@ static inline void NBC_Free (NBC_Handle* handle) {
  * to be called *only* from the progress thread !!! */
 int NBC_Progress(NBC_Handle *handle) {
   int flag, res, ret=NBC_CONTINUE;
-  unsigned long size;
+  unsigned long size = 0;
   char *delim;
 
   /* the handle is done if there is no schedule attached */
diff --git a/ompi/mca/io/ompio/io_ompio.c b/ompi/mca/io/ompio/io_ompio.c
index 1b08917de4..7d93402606 100644
--- a/ompi/mca/io/ompio/io_ompio.c
+++ b/ompi/mca/io/ompio/io_ompio.c
@@ -2002,6 +2002,7 @@ int ompi_io_ompio_empty_print_queue(int queue_type){
     ret =  ompi_io_ompio_set_print_queue(&q, queue_type);
 
     assert (ret != OMPI_ERROR);
+    (void)ret;  // silence compiler warning
     if (q->count == 0)
 	    return 1;
     else
@@ -2018,6 +2019,7 @@ int ompi_io_ompio_full_print_queue(int queue_type){
     ret =  ompi_io_ompio_set_print_queue(&q, queue_type);
 
     assert ( ret != OMPI_ERROR);
+    (void)ret;  // silence compiler warning
     if (q->count < QUEUESIZE)
 	    return 0;
     else
diff --git a/ompi/mca/osc/pt2pt/osc_pt2pt_data_move.c b/ompi/mca/osc/pt2pt/osc_pt2pt_data_move.c
index 6883d79a4a..77ea7f861f 100644
--- a/ompi/mca/osc/pt2pt/osc_pt2pt_data_move.c
+++ b/ompi/mca/osc/pt2pt/osc_pt2pt_data_move.c
@@ -1618,6 +1618,7 @@ static int ompi_osc_pt2pt_callback (ompi_request_t *request)
     OPAL_THREAD_UNLOCK(&ompi_request_lock);
 
     assert(incoming_length >= sizeof(ompi_osc_pt2pt_header_base_t));
+    (void)incoming_length;  // silence compiler warning
 
     OPAL_OUTPUT_VERBOSE((50, ompi_osc_base_framework.framework_output,
                          "received pt2pt callback for fragment. source = %d, count = %u, type = 0x%x",
diff --git a/ompi/mca/osc/rdma/osc_rdma_active_target.c b/ompi/mca/osc/rdma/osc_rdma_active_target.c
index 16dc2aa3eb..bc0117dc1d 100644
--- a/ompi/mca/osc/rdma/osc_rdma_active_target.c
+++ b/ompi/mca/osc/rdma/osc_rdma_active_target.c
@@ -180,8 +180,8 @@ int ompi_osc_rdma_post_atomic (ompi_group_t *group, int assert, ompi_win_t *win)
     int my_rank = ompi_comm_rank (module->comm);
     ompi_osc_rdma_state_t *state = module->state;
     volatile bool atomic_complete;
-    ompi_osc_rdma_frag_t *frag;
-    osc_rdma_counter_t *temp;
+    ompi_osc_rdma_frag_t *frag = NULL;
+    osc_rdma_counter_t *temp = NULL;
     int ret;
 
     OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_TRACE, "post: %p, %d, %s", (void*) group, assert, win->w_name);
diff --git a/ompi/mca/osc/rdma/osc_rdma_peer.c b/ompi/mca/osc/rdma/osc_rdma_peer.c
index 8b59607cf9..fce5092823 100644
--- a/ompi/mca/osc/rdma/osc_rdma_peer.c
+++ b/ompi/mca/osc/rdma/osc_rdma_peer.c
@@ -179,6 +179,7 @@ static int ompi_osc_rdma_peer_setup (ompi_osc_rdma_module_t *module, ompi_osc_rd
     OSC_RDMA_VERBOSE(MCA_BASE_VERBOSE_DEBUG, "peer %d: remote base region: 0x%" PRIx64 ", size: %" PRId64
                      ", flags: 0x%x, disp_unit: %d", peer->rank, base_region->base, base_region->len,
                      peer->flags, disp_unit);
+    (void)disp_unit;  // silence compiler warning
 
     if (ompi_osc_rdma_peer_local_base (peer)) {
         /* for now we store the local address in the standard place. do no overwrite it */
diff --git a/ompi/mca/pml/v/pml_v_output.h b/ompi/mca/pml/v/pml_v_output.h
index 13c9c1e482..77bb5b1405 100644
--- a/ompi/mca/pml/v/pml_v_output.h
+++ b/ompi/mca/pml/v/pml_v_output.h
@@ -30,6 +30,7 @@ static inline void V_OUTPUT_ERR(const char *fmt, ... )
     va_start(list, fmt);
     ret = vasprintf(&str, fmt, list);
     assert(-1 != ret);
+    (void)ret;  // silence compiler warning
     opal_output(0, "%s", str);
     free(str);
     va_end(list);