diff --git a/src/H5.c b/src/H5.c
index 538925ca963..25691276c18 100644
--- a/src/H5.c
+++ b/src/H5.c
@@ -1222,10 +1222,12 @@ H5allocate_memory(size_t size, hbool_t clear)
     FUNC_ENTER_API_NOINIT
     H5TRACE2("*x", "zb", size, clear);
 
-    if (clear)
-        ret_value = H5MM_calloc(size);
-    else
-        ret_value = H5MM_malloc(size);
+    if (size != 0) {
+        if (clear)
+            ret_value = H5MM_calloc(size);
+        else
+            ret_value = H5MM_malloc(size);
+    }
 
     FUNC_LEAVE_API_NOINIT(ret_value)
 } /* end H5allocate_memory() */
@@ -1262,7 +1264,10 @@ H5resize_memory(void *mem, size_t size)
     FUNC_ENTER_API_NOINIT
     H5TRACE2("*x", "*xz", mem, size);
 
-    ret_value = H5MM_realloc(mem, size);
+    if (size != 0)
+        ret_value = H5MM_realloc(mem, size);
+    else if (mem)
+        ret_value = H5MM_xfree(mem);
 
     FUNC_LEAVE_API_NOINIT(ret_value)
 } /* end H5resize_memory() */
diff --git a/src/H5MM.c b/src/H5MM.c
index 9c03ceb338d..40634e2d35a 100644
--- a/src/H5MM.c
+++ b/src/H5MM.c
@@ -232,7 +232,6 @@ H5MM_final_sanity_check(void)
     HDfprintf(stderr, "%s: H5MM_peak_alloc_blocks_count_s = %zu\n", __func__, H5MM_peak_alloc_blocks_count_s);
 #endif /* H5MM_PRINT_MEMORY_STATS */
 }
-#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
 
 /*-------------------------------------------------------------------------
  * Function:    H5MM_malloc
@@ -261,7 +260,6 @@ H5MM_malloc(size_t size)
     /* Use FUNC_ENTER_NOAPI_NOINIT_NOERR here to avoid performance issues */
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
-#if defined H5_MEMORY_ALLOC_SANITY_CHECK
     /* Initialize block list head singleton */
     if (!H5MM_init_s) {
         H5MM_memcpy(H5MM_block_head_s.sig, H5MM_block_signature_s, H5MM_SIG_SIZE);
@@ -271,11 +269,9 @@ H5MM_malloc(size_t size)
         H5MM_block_head_s.u.info.in_use = TRUE;
 
         H5MM_init_s = TRUE;
-    }  /* end if */
-#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
+    } /* end if */
 
     if (size) {
-#if defined H5_MEMORY_ALLOC_SANITY_CHECK
         H5MM_block_t *block;
         size_t        alloc_size = sizeof(H5MM_block_t) + size + H5MM_HEAD_GUARD_SIZE + H5MM_TAIL_GUARD_SIZE;
 
@@ -309,10 +305,7 @@ H5MM_malloc(size_t size)
         } /* end if */
         else
             ret_value = NULL;
-#else  /* H5_MEMORY_ALLOC_SANITY_CHECK */
-        ret_value = HDmalloc(size);
-#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
-    }  /* end if */
+    } /* end if */
     else
         ret_value = NULL;
 
@@ -349,13 +342,9 @@ H5MM_calloc(size_t size)
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
     if (size) {
-#if defined H5_MEMORY_ALLOC_SANITY_CHECK
         if (NULL != (ret_value = H5MM_malloc(size)))
             HDmemset(ret_value, 0, size);
-#else  /* H5_MEMORY_ALLOC_SANITY_CHECK */
-        ret_value = HDcalloc((size_t)1, size);
-#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
-    }  /* end if */
+    } /* end if */
     else
         ret_value = NULL;
 
@@ -396,7 +385,6 @@ H5MM_realloc(void *mem, size_t size)
         /* Not defined in the standard, return NULL */
         ret_value = NULL;
     else {
-#if defined H5_MEMORY_ALLOC_SANITY_CHECK
         if (size > 0) {
             if (mem) {
                 if (H5MM__is_our_block(mem)) {
@@ -417,17 +405,11 @@ H5MM_realloc(void *mem, size_t size)
         }
         else
             ret_value = H5MM_xfree(mem);
-#else  /* H5_MEMORY_ALLOC_SANITY_CHECK */
-        ret_value = HDrealloc(mem, size);
-
-        /* Some platforms do not return NULL if size is zero. */
-        if (0 == size)
-            ret_value = NULL;
-#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
-    }  /* end else */
+    } /* end else */
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5MM_realloc() */
+#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
 
 /*-------------------------------------------------------------------------
  * Function:    H5MM_xstrdup
@@ -465,6 +447,7 @@ H5MM_xstrdup(const char *s)
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5MM_xstrdup() */
 
+#if defined H5_MEMORY_ALLOC_SANITY_CHECK
 /*-------------------------------------------------------------------------
  * Function:    H5MM_strdup
  *
@@ -490,14 +473,9 @@ H5MM_strdup(const char *s)
 
     if (!s)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "NULL string not allowed")
-#if defined H5_MEMORY_ALLOC_SANITY_CHECK
     if (NULL == (ret_value = (char *)H5MM_malloc(HDstrlen(s) + 1)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
     HDstrcpy(ret_value, s);
-#else
-    if (NULL == (ret_value = HDstrdup(s)))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "string duplication failed")
-#endif
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -522,17 +500,14 @@ H5MM_strdup(const char *s)
 char *
 H5MM_strndup(const char *s, size_t n)
 {
-#if defined H5_MEMORY_ALLOC_SANITY_CHECK
     size_t len;
-#endif
-    char *ret_value = NULL;
+    char  *ret_value = NULL;
 
     FUNC_ENTER_NOAPI(NULL)
 
     if (!s)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "NULL string not allowed")
 
-#if defined H5_MEMORY_ALLOC_SANITY_CHECK
     for (len = 0; len < n && s[len] != '\0'; len++)
         ;
 
@@ -541,14 +516,11 @@ H5MM_strndup(const char *s, size_t n)
 
     H5MM_memcpy(ret_value, s, len);
     ret_value[len] = '\0';
-#else
-    if (NULL == (ret_value = HDstrndup(s, n)))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "string duplication failed")
-#endif
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5MM_strndup() */
+#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
 
 /*-------------------------------------------------------------------------
  * Function:    H5MM_xfree
@@ -632,6 +604,7 @@ H5MM_xfree_const(const void *mem)
     FUNC_LEAVE_NOAPI(NULL)
 } /* end H5MM_xfree_const() */
 
+#if defined H5_MEMORY_ALLOC_SANITY_CHECK
 /*-------------------------------------------------------------------------
  * Function:    H5MM_memcpy
  *
@@ -666,6 +639,7 @@ H5MM_memcpy(void *dest, const void *src, size_t n)
     FUNC_LEAVE_NOAPI(ret)
 
 } /* end H5MM_memcpy() */
+#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
 
 /*-------------------------------------------------------------------------
  * Function:	H5MM_get_alloc_stats
diff --git a/src/H5MMprivate.h b/src/H5MMprivate.h
index 0a5a0111348..2a316c02918 100644
--- a/src/H5MMprivate.h
+++ b/src/H5MMprivate.h
@@ -30,28 +30,45 @@
 #include "H5private.h"
 
 #if defined H5_MEMORY_ALLOC_SANITY_CHECK
-/*#define H5MM_PRINT_MEMORY_STATS */
-#define H5MM_free(Z) H5MM_xfree(Z)
-#else /* H5_MEMORY_ALLOC_SANITY_CHECK */
-#define H5MM_free(Z) HDfree(Z)
-#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
+
+/*
+ * Define this to have the library print out memory
+ * statistics during its final memory sanity checking
+ */
+/*#define H5MM_PRINT_MEMORY_STATS*/
+
+#define H5MM_free(ptr) H5MM_xfree(ptr)
+
+/*
+ * Library prototypes...
+ */
+H5_DLL void *H5MM_malloc(size_t size) H5_ATTR_MALLOC;
+H5_DLL void *H5MM_calloc(size_t size) H5_ATTR_MALLOC;
+H5_DLL void *H5MM_realloc(void *mem, size_t size);
+H5_DLL char *H5MM_strdup(const char *s);
+H5_DLL char *H5MM_strndup(const char *s, size_t n);
+H5_DLL void *H5MM_memcpy(void *dest, const void *src, size_t n);
+H5_DLL void  H5MM_sanity_check_all(void);
+H5_DLL void  H5MM_final_sanity_check(void);
+
+#else
+
+#define H5MM_malloc(size)        HDmalloc(size)
+#define H5MM_calloc(size)        HDcalloc(1, size)
+#define H5MM_realloc(ptr, size)  HDrealloc(ptr, size)
+#define H5MM_free(ptr)           HDfree(ptr)
+#define H5MM_strdup(s)           HDstrdup(s)
+#define H5MM_strndup(s, n)       HDstrndup(s, n)
+#define H5MM_memcpy(dst, src, n) HDmemcpy(dst, src, n)
+
+#endif
 
 /*
  * Library prototypes...
  */
-H5_DLL void  *H5MM_malloc(size_t size) H5_ATTR_MALLOC;
-H5_DLL void  *H5MM_calloc(size_t size) H5_ATTR_MALLOC;
-H5_DLL void  *H5MM_realloc(void *mem, size_t size);
-H5_DLL char  *H5MM_xstrdup(const char *s);
-H5_DLL char  *H5MM_strdup(const char *s);
-H5_DLL char  *H5MM_strndup(const char *s, size_t n);
 H5_DLL void  *H5MM_xfree(void *mem);
 H5_DLL void  *H5MM_xfree_const(const void *mem);
-H5_DLL void  *H5MM_memcpy(void *dest, const void *src, size_t n);
+H5_DLL char  *H5MM_xstrdup(const char *s);
 H5_DLL herr_t H5MM_get_alloc_stats(H5_alloc_stats_t *stats);
-#if defined   H5_MEMORY_ALLOC_SANITY_CHECK
-H5_DLL void   H5MM_sanity_check_all(void);
-H5_DLL void   H5MM_final_sanity_check(void);
-#endif /* H5_MEMORY_ALLOC_SANITY_CHECK */
 
 #endif /* H5MMprivate_H */
diff --git a/test/tmisc.c b/test/tmisc.c
index 429b275f576..3bb9192d280 100644
--- a/test/tmisc.c
+++ b/test/tmisc.c
@@ -5826,6 +5826,7 @@ test_misc34(void)
     mem = H5MM_xfree(mem);
     CHECK_PTR_NULL(mem, "H5MM_xfree");
 
+#if defined H5_MEMORY_ALLOC_SANITY_CHECK
     /* H5MM_malloc(): Ensure that size 0 returns NULL */
     mem = H5MM_malloc(sz);
     CHECK_PTR_NULL(mem, "H5MM_malloc");
@@ -5835,6 +5836,7 @@ test_misc34(void)
     mem = H5MM_calloc(sz);
     CHECK_PTR_NULL(mem, "H5MM_calloc");
     mem = H5MM_xfree(mem);
+#endif
 
     /* H5MM_realloc(): Check behavior:
      *
@@ -5849,6 +5851,7 @@ test_misc34(void)
     CHECK_PTR(mem, "H5MM_realloc (case 1)");
     /* Don't free mem here! */
 
+#if defined H5_MEMORY_ALLOC_SANITY_CHECK
     sz  = 0;
     mem = H5MM_realloc(mem, sz);
     CHECK_PTR_NULL(mem, "H5MM_realloc (case 2)");
@@ -5856,6 +5859,8 @@ test_misc34(void)
 
     mem = H5MM_realloc(mem, sz);
     CHECK_PTR_NULL(mem, "H5MM_realloc (case 3)");
+#endif
+
     mem = H5MM_xfree(mem);
 
     /* H5MM_xstrdup(): Ensure NULL returns NULL */