diff --git a/src/H5FDmulti.c b/src/H5FDmulti.c
index 168bbe162eb..92266244f2f 100644
--- a/src/H5FDmulti.c
+++ b/src/H5FDmulti.c
@@ -35,6 +35,15 @@
 #define TRUE 1
 #endif
 
+/* Windows doesn't like some POSIX names and redefines them with an
+ * underscore
+ */
+#ifdef _WIN32
+#define my_strdup _strdup
+#else
+#define my_strdup strdup
+#endif
+
 /* Loop through all mapped files */
 #define UNIQUE_MEMBERS_CORE(MAP, ITER, SEEN, LOOPVAR)                                                        \
     {                                                                                                        \
@@ -103,9 +112,8 @@ typedef struct H5FD_multi_dxpl_t {
 } H5FD_multi_dxpl_t;
 
 /* Private functions */
-static char *my_strdup(const char *s);
-static int   compute_next(H5FD_multi_t *file);
-static int   open_members(H5FD_multi_t *file);
+static int compute_next(H5FD_multi_t *file);
+static int open_members(H5FD_multi_t *file);
 
 /* Callback prototypes */
 static herr_t  H5FD_multi_term(void);
@@ -171,36 +179,6 @@ static const H5FD_class_t H5FD_multi_g = {
     H5FD_FLMAP_DEFAULT         /*fl_map        */
 };
 
-/*-------------------------------------------------------------------------
- * Function:    my_strdup
- *
- * Purpose:    Private version of strdup()
- *
- * Return:    Success:    Ptr to new copy of string
- *
- *            Failure:    NULL
- *
- * Programmer:    Robb Matzke
- *              Friday, August 13, 1999
- *
- *-------------------------------------------------------------------------
- */
-static char *
-my_strdup(const char *s)
-{
-    char * x;
-    size_t str_len;
-
-    if (!s)
-        return NULL;
-    str_len = strlen(s) + 1;
-    if (NULL == (x = (char *)malloc(str_len)))
-        return NULL;
-    memcpy(x, s, str_len);
-
-    return x;
-}
-
 /*-------------------------------------------------------------------------
  * Function:    H5FD_multi_init
  *
diff --git a/src/H5MM.c b/src/H5MM.c
index d17db16e262..b4447f61e77 100644
--- a/src/H5MM.c
+++ b/src/H5MM.c
@@ -449,11 +449,17 @@ H5MM_xstrdup(const char *s)
 
     FUNC_ENTER_NOAPI(NULL)
 
+#if defined H5_MEMORY_ALLOC_SANITY_CHECK
     if (s) {
         if (NULL == (ret_value = (char *)H5MM_malloc(HDstrlen(s) + 1)))
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
         HDstrcpy(ret_value, s);
-    } /* end if */
+    }
+#else
+    if (s)
+        if (NULL == (ret_value = HDstrdup(s)))
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "string duplication failed")
+#endif
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -483,10 +489,15 @@ H5MM_strdup(const char *s)
     FUNC_ENTER_NOAPI(NULL)
 
     if (!s)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "null string")
+        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)
diff --git a/src/H5private.h b/src/H5private.h
index 0d6377c7273..efc19d3381e 100644
--- a/src/H5private.h
+++ b/src/H5private.h
@@ -1484,6 +1484,9 @@ H5_DLL void HDsrand(unsigned int seed);
 #ifndef HDstrcspn
 #define HDstrcspn(X, Y) strcspn(X, Y)
 #endif /* HDstrcspn */
+#ifndef HDstrdup
+#define HDstrdup(S) strdup(S)
+#endif /* HDstrdup */
 #ifndef HDstrerror
 #define HDstrerror(N) strerror(N)
 #endif /* HDstrerror */
@@ -1672,18 +1675,6 @@ H5_DLL int     HDvasprintf(char **bufp, const char *fmt, va_list _ap);
 #define HDwrite(F, M, Z) write(F, M, Z)
 #endif /* HDwrite */
 
-/*
- * And now for a couple non-Posix functions...  Watch out for systems that
- * define these in terms of macros.
- */
-#if !defined strdup && !defined H5_HAVE_STRDUP
-extern char *                   strdup(const char *s);
-#endif
-
-#ifndef HDstrdup
-#define HDstrdup(S) strdup(S)
-#endif /* HDstrdup */
-
 /* Macro for "stringizing" an integer in the C preprocessor (use H5_TOSTRING) */
 /* (use H5_TOSTRING, H5_STRINGIZE is just part of the implementation) */
 #define H5_STRINGIZE(x) #x