diff --git a/lib/stdio/fputc.c b/lib/stdio/fputc.c
index 232b534a..4931e710 100644
--- a/lib/stdio/fputc.c
+++ b/lib/stdio/fputc.c
@@ -23,5 +23,5 @@
 int
 fputc (int c, FILE * stream)
 {
-  return fdputc (c, (int) stream);
+  return fdputc (c, (long) stream);
 }
diff --git a/lib/stdlib/malloc.c b/lib/stdlib/malloc.c
index 940f95b5..e16f0036 100644
--- a/lib/stdlib/malloc.c
+++ b/lib/stdlib/malloc.c
@@ -24,7 +24,7 @@ void *
 malloc (size_t size)
 {
   if (!__brk)
-    __brk = brk (0);
+    __brk = (char *) brk (0);
   if (brk (__brk + size) == -1)
     return 0;
   char *p = __brk;
diff --git a/lib/string/memchr.c b/lib/string/memchr.c
index eac13a9f..66485d4b 100644
--- a/lib/string/memchr.c
+++ b/lib/string/memchr.c
@@ -27,7 +27,7 @@ memchr (void const *block, int c, size_t size)
   while (size--)
     {
       if (c == *p)
-        return p;
+        return (void *) p;
       p++;
     }
   return 0;
diff --git a/lib/string/memcmp.c b/lib/string/memcmp.c
index 1d67e202..5c28af8c 100644
--- a/lib/string/memcmp.c
+++ b/lib/string/memcmp.c
@@ -25,8 +25,8 @@ memcmp (void const *s1, void const *s2, size_t size)
 {
   if (!size)
     return 0;
-  char *a = s1;
-  char *b = s2;
+  char const *a = s1;
+  char const *b = s2;
   while (*a == *b && --size)
     {
       a++;