diff --git a/sys/libc/calloc.c b/sys/libc/calloc.c
index f9a4f044d..5e5677a2b 100644
--- a/sys/libc/calloc.c
+++ b/sys/libc/calloc.c
@@ -10,7 +10,7 @@
 /* CALLOC -- Allocate memory for NELEM elements of size ELSIZE bytes per
 ** element.  The space is initialized to all zeros.
 */
-char *
+void *
 calloc (
   unsigned int nelems,
   unsigned int elsize
diff --git a/sys/libc/free.c b/sys/libc/free.c
index 4edd18c07..668825530 100644
--- a/sys/libc/free.c
+++ b/sys/libc/free.c
@@ -12,7 +12,7 @@
 */
 void
 free (
-  char	*buf
+  void	*buf
 )
 {
 	XINT	x_ptr, x_dtype = TY_CHAR;
diff --git a/sys/libc/malloc.c b/sys/libc/malloc.c
index af5506cfa..b5124d7c8 100644
--- a/sys/libc/malloc.c
+++ b/sys/libc/malloc.c
@@ -9,7 +9,7 @@
 
 /* MALLOC -- Allocate an uninitialized block of memory at least nbytes in size.
 */
-char *
+void *
 malloc (
   unsigned nbytes
 )
@@ -20,5 +20,5 @@ malloc (
 	iferr (MALLOC (&x_ptr, &x_nchars, &x_dtype))
 	    return (NULL);
 	else
-	    return ((char *)&Memc[x_ptr]);
+	    return ((void *)&Memc[x_ptr]);
 }
diff --git a/sys/libc/realloc.c b/sys/libc/realloc.c
index 672cc7770..35986ed7d 100644
--- a/sys/libc/realloc.c
+++ b/sys/libc/realloc.c
@@ -11,9 +11,9 @@
 ** allocated buffer.  If necessary the buffer is moved, preserving any
 ** data in the buffer.
 */
-char *
+void *
 realloc (
-  char	*buf,
+  void	*buf,
   unsigned newsize
 )
 {
@@ -24,5 +24,5 @@ realloc (
 	iferr (REALLOC (&x_ptr, &x_nchars, &x_dtype))
 	    return (NULL);
 	else
-	    return ((char *)&Memc[x_ptr]);
+	    return ((void *)&Memc[x_ptr]);
 }
diff --git a/unix/hlib/libc/iraf_libc.h b/unix/hlib/libc/iraf_libc.h
index 4e68f6b38..f760a1184 100644
--- a/unix/hlib/libc/iraf_libc.h
+++ b/unix/hlib/libc/iraf_libc.h
@@ -124,14 +124,14 @@ extern char    *c_cnvtime (long clktime, char *outstr, int maxch);
 extern char    *c_getuid (char *outstr, int maxch);
 extern char    *c_salloc (unsigned nbytes);
 extern char    *c_strpak (short *sppstr, char *cstr, int maxch);
-extern char    *calloc (unsigned int nelems, unsigned int elsize);
+extern void    *calloc (unsigned int nelems, unsigned int elsize);
 extern char    *envget (char *var);
 extern char    *fgets (char *buf, int maxch, struct _iobuf *fp);
 extern char    *gets (char *buf);
-extern char    *malloc (unsigned nbytes);
+extern void    *malloc (unsigned nbytes);
 extern char    *mktemp (char *template);
 extern char    *freadline (char *prompt);
-extern char    *realloc (char *buf, unsigned newsize);
+extern void    *realloc (void *buf, unsigned newsize);
 extern char    *sprintf (char *str, char *format, ...);
 
 extern double   atof (char *str);
@@ -285,7 +285,7 @@ extern void	c_xwhen (int exception, funcptr_t new_handler, funcptr_t *old_handle
 extern void	eprintf (char *format, ...);
 extern void	fprintf (struct _iobuf *fp, char *format, ...);
 extern void	fputs (char *str, struct _iobuf *fp);
-extern void	free (char *buf);
+extern void	free (void *buf);
 extern void	perror (char *prefix);
 extern void	printf (char *format, ...);
 extern void	setbuf (struct _iobuf *fp, char *buf);