diff --git a/ompi/mca/io/romio321/romio/adio/common/onesided_aggregation.c b/ompi/mca/io/romio321/romio/adio/common/onesided_aggregation.c
index 3e0ad1f8fcd..71a5b7bee6e 100644
--- a/ompi/mca/io/romio321/romio/adio/common/onesided_aggregation.c
+++ b/ompi/mca/io/romio321/romio/adio/common/onesided_aggregation.c
@@ -1966,7 +1966,7 @@ printf("iAmUsedAgg - currentRoundFDStart initialized "
       int *sourceAggBlockLengths=NULL;
       MPI_Aint *sourceAggDisplacements=NULL, *recvBufferDisplacements=NULL;
       MPI_Datatype *sourceAggDataTypes=NULL;
-      char *derivedTypePackedSourceBuffer;
+      char *derivedTypePackedSourceBuffer=NULL;
       int derivedTypePackedSourceBufferOffset = 0;
       int allocatedDerivedTypeArrays = 0;
       ADIO_Offset amountOfDataReadThisRoundAgg = 0;