diff --git a/c/src/exec/libcsupport/src/malloc.c b/c/src/exec/libcsupport/src/malloc.c
index e8387d4364..35acf86a2f 100644
--- a/c/src/exec/libcsupport/src/malloc.c
+++ b/c/src/exec/libcsupport/src/malloc.c
@@ -26,6 +26,11 @@
 #include <assert.h>
 #include <errno.h>
 #include <string.h>
+
+/* for sbrk prototype in linux */
+#if defined(linux)
+#define __USE_MISC
+#endif
 #include <unistd.h>    /* sbrk(2) */
 
 rtems_id RTEMS_Malloc_Heap;
diff --git a/c/src/lib/libc/malloc.c b/c/src/lib/libc/malloc.c
index e8387d4364..35acf86a2f 100644
--- a/c/src/lib/libc/malloc.c
+++ b/c/src/lib/libc/malloc.c
@@ -26,6 +26,11 @@
 #include <assert.h>
 #include <errno.h>
 #include <string.h>
+
+/* for sbrk prototype in linux */
+#if defined(linux)
+#define __USE_MISC
+#endif
 #include <unistd.h>    /* sbrk(2) */
 
 rtems_id RTEMS_Malloc_Heap;
diff --git a/cpukit/libcsupport/src/malloc.c b/cpukit/libcsupport/src/malloc.c
index e8387d4364..35acf86a2f 100644
--- a/cpukit/libcsupport/src/malloc.c
+++ b/cpukit/libcsupport/src/malloc.c
@@ -26,6 +26,11 @@
 #include <assert.h>
 #include <errno.h>
 #include <string.h>
+
+/* for sbrk prototype in linux */
+#if defined(linux)
+#define __USE_MISC
+#endif
 #include <unistd.h>    /* sbrk(2) */
 
 rtems_id RTEMS_Malloc_Heap;