diff --git a/newlib/libc/stdlib/nano-mallocr.c b/newlib/libc/stdlib/nano-mallocr.c
index 8d6ca5ce0..4a2f4680e 100644
--- a/newlib/libc/stdlib/nano-mallocr.c
+++ b/newlib/libc/stdlib/nano-mallocr.c
@@ -46,6 +46,8 @@
 #define MAX(a,b) ((a) >= (b) ? (a) : (b))
 #endif
 
+#define _SBRK_R(X) _sbrk_r(X)
+
 #ifdef INTERNAL_NEWLIB
 
 #include <sys/config.h>
@@ -209,9 +211,9 @@ static void* sbrk_aligned(RARG malloc_size_t s)
 {
     char *p, *align_p;
 
-    if (sbrk_start == NULL) sbrk_start = _sbrk_r(RCALL 0);
+    if (sbrk_start == NULL) sbrk_start = _SBRK_R(RCALL 0);
 
-    p = _sbrk_r(RCALL s);
+    p = _SBRK_R(RCALL s);
 
     /* sbrk returns -1 if fail to allocate */
     if (p == (void *)-1)
@@ -222,7 +224,7 @@ static void* sbrk_aligned(RARG malloc_size_t s)
     {
         /* p is not aligned, ask for a few more bytes so that we have s
          * bytes reserved from align_p. */
-        p = _sbrk_r(RCALL align_p - p);
+        p = _SBRK_R(RCALL align_p - p);
         if (p == (void *)-1)
             return p;
     }
@@ -486,7 +488,7 @@ struct mallinfo nano_mallinfo(RONEARG)
 
     if (sbrk_start == NULL) total_size = 0;
     else {
-        sbrk_now = _sbrk_r(RCALL 0);
+        sbrk_now = _SBRK_R(RCALL 0);
 
         if (sbrk_now == (void *)-1)
             total_size = (size_t)-1;