diff --git a/c++/test/trefer.cpp b/c++/test/trefer.cpp
index ecc6de6c972..4a9a2f0447b 100644
--- a/c++/test/trefer.cpp
+++ b/c++/test/trefer.cpp
@@ -555,10 +555,10 @@ test_reference_region_1D()
             *drbuf;            // Buffer for reading numeric data from disk
 
         // Allocate write & read buffers
-        wbuf  = static_cast<hdset_reg_ref_t *>(calloc(sizeof(hdset_reg_ref_t), SPACE1_DIM1));
-        rbuf  = static_cast<hdset_reg_ref_t *>(malloc(sizeof(hdset_reg_ref_t) * SPACE1_DIM1));
-        dwbuf = static_cast<uint8_t *>(malloc(sizeof(uint8_t) * SPACE3_DIM1));
-        drbuf = static_cast<uint8_t *>(calloc(sizeof(uint8_t), SPACE3_DIM1));
+        wbuf  = static_cast<hdset_reg_ref_t *>(calloc(SPACE1_DIM1, sizeof(hdset_reg_ref_t)));
+        rbuf  = static_cast<hdset_reg_ref_t *>(calloc(SPACE1_DIM1, sizeof(hdset_reg_ref_t)));
+        dwbuf = static_cast<uint8_t *>(calloc(SPACE3_DIM1, sizeof(uint8_t)));
+        drbuf = static_cast<uint8_t *>(calloc(SPACE3_DIM1, sizeof(uint8_t)));
 
         // Create file FILE1
         H5File file1(FILE2, H5F_ACC_TRUNC);
diff --git a/tools/src/h5repack/h5repack_refs.c b/tools/src/h5repack/h5repack_refs.c
index 0c281b006e8..95f396663af 100644
--- a/tools/src/h5repack/h5repack_refs.c
+++ b/tools/src/h5repack/h5repack_refs.c
@@ -631,7 +631,7 @@ copy_refs_attr(hid_t loc_in, hid_t loc_out, trav_table_t *travt, hid_t fidout) /
                  * create output
                  *-------------------------------------------------------------------------
                  */
-                refbuf = (hdset_reg_ref_t *)calloc(sizeof(hdset_reg_ref_t), (size_t)nelmts); /*init to zero */
+                refbuf = (hdset_reg_ref_t *)calloc((size_t)nelmts, sizeof(hdset_reg_ref_t)); /*init to zero */
                 if (refbuf == NULL) {
                     printf("cannot allocate memory\n");
                     H5TOOLS_GOTO_ERROR((-1), "calloc failed");
diff --git a/tools/test/h5dump/h5dumpgentest.c b/tools/test/h5dump/h5dumpgentest.c
index 2a06a2323a3..c81d114164f 100644
--- a/tools/test/h5dump/h5dumpgentest.c
+++ b/tools/test/h5dump/h5dumpgentest.c
@@ -2406,10 +2406,10 @@ gent_attrreg(void)
     int              i;                                   /* counting variables */
 
     /* Allocate write & read buffers */
-    wbuf  = (hdset_reg_ref_t *)calloc(sizeof(hdset_reg_ref_t), SPACE1_DIM1);
-    rbuf  = (hdset_reg_ref_t *)malloc(sizeof(hdset_reg_ref_t) * SPACE1_DIM1);
-    dwbuf = (uint8_t *)malloc(sizeof(uint8_t) * SPACE2_DIM1 * SPACE2_DIM2);
-    drbuf = (uint8_t *)calloc(sizeof(uint8_t), SPACE2_DIM1 * SPACE2_DIM2);
+    wbuf  = (hdset_reg_ref_t *)calloc(SPACE1_DIM1, sizeof(hdset_reg_ref_t));
+    rbuf  = (hdset_reg_ref_t *)calloc(SPACE1_DIM1, sizeof(hdset_reg_ref_t));
+    dwbuf = (uint8_t *)calloc(SPACE2_DIM1 * SPACE2_DIM2, sizeof(uint8_t));
+    drbuf = (uint8_t *)calloc(SPACE2_DIM1 * SPACE2_DIM2, sizeof(uint8_t));
 
     /* Create file */
     fid1 = H5Fcreate(FILE64, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
@@ -3121,7 +3121,7 @@ gent_array1_big(void)
     block[0]  = 1;
 
     /* Allocate write & read buffers */
-    wbuf  = (hdset_reg_ref_t *)calloc(sizeof(hdset_reg_ref_t), SPACE1_DIM1);
+    wbuf  = (hdset_reg_ref_t *)calloc(SPACE1_DIM1, sizeof(hdset_reg_ref_t));
     wdata = (int *)malloc(sizeof(int) * (size_t)(SPACE_ARRAY1BIG_DIM * ARRAY1BIG_DIM));
 
     /* Allocate and initialize array data to write */