diff --git a/lang/cem/libcc.ansi/headers/grp.h b/lang/cem/libcc.ansi/headers/grp.h
index d881f3b73..6d9d6939b 100644
--- a/lang/cem/libcc.ansi/headers/grp.h
+++ b/lang/cem/libcc.ansi/headers/grp.h
@@ -6,7 +6,11 @@
 struct	group {				/* see getgrent(3) */
 	char	*gr_name;
 	char	*gr_passwd;
+#if	defined(_POSIX_SOURCE) && defined(_MINIX)
+	char	gr_gid;
+#else
 	int	gr_gid;
+#endif
 	char	**gr_mem;
 };
 
diff --git a/lang/cem/libcc.ansi/headers/setjmp.h b/lang/cem/libcc.ansi/headers/setjmp.h
index 74fbdaab1..d5b636f2a 100644
--- a/lang/cem/libcc.ansi/headers/setjmp.h
+++ b/lang/cem/libcc.ansi/headers/setjmp.h
@@ -9,9 +9,24 @@
 #if	!defined(_SETJMP_H)
 #define	_SETJMP_H
 
-typedef char jmp_buf[256];
+/* In a jmp_buf, there is room for:  1 mask (long), 1 flag (int) and 3
+ * pointers (stack-pointer, local base and program-counter). This may be
+ * too big, but that doesn't matter. It could also be too small, when
+ * sigset_t is larger than a long.
+ * The identifier __setjmp has a special meaning to the compiler.
+ */
 
-int	setjmp(jmp_buf __env);
+typedef char jmp_buf[ sizeof(long) + sizeof(int) + 3 * sizeof(void *)];
+
+int	__setjmp(jmp_buf __env, int __savemask);
+
+#define	setjmp(env)	__setjmp(env, 0)
 void	longjmp(jmp_buf __env, int __val);
 
+#if defined(_POSIX_SOURCE)
+typedef jmp_buf sigjmp_buf;
+#define	sigsetjmp(env, savemask)	__setjmp(env, savemask)
+int	siglongjmp(sigjmp_buf __env, int __val);
+#endif
+
 #endif	/* _SETJMP_H */
diff --git a/lang/cem/libcc.ansi/headers/signal.h b/lang/cem/libcc.ansi/headers/signal.h
index 4a519e2dd..f4c226c20 100644
--- a/lang/cem/libcc.ansi/headers/signal.h
+++ b/lang/cem/libcc.ansi/headers/signal.h
@@ -11,6 +11,22 @@
 
 typedef	int		sig_atomic_t;
 
+#if	defined(_POSIX_SOURCE)
+#if	defined(_MINIX)
+typedef	unsigned short sigset_t;
+
+#define	SIG_BLOCK	0	/* for blocking signals */
+#define	SIG_UNBLOCK	1	/* for unblocking signals */
+#define	SIG_SETMASK	2	/* for setting the signal mask */
+
+struct sigaction {
+	void (*sa_handler)(int);/* SIG_DFL, SIG_IGN or pointer to function */
+	sigset_t sa_mask;	/* signals blocked during handling */
+	int sa_flags;		/* special flags */
+};
+#endif
+#endif
+
 #define	SIG_ERR		((void (*)(int))-1)
 #if	defined(em22) || defined(em24) || defined(em44)
 #define	SIG_DFL		((void (*)(int))-2)
@@ -62,6 +78,15 @@ typedef	int		sig_atomic_t;
 #define SIGUSR1 30	/* user defined signal 1 */
 #define SIGUSR2 31	/* user defined signal 2 */
 #define	_NSIG	32
+#elif	defined(_MINIX)
+/* The following signals are defined but not supported */
+#define SIGCHLD		17	/* child process terminated or stopped */
+#define SIGCONT		18	/* continue if stopped */
+#define SIGSTOP		19	/* stop signal */
+#define SIGTSTP		20	/* interactive stop signal */
+#define SIGTTIN		21	/* background process wants to read */
+#define SIGTTOU		22	/* background process wants to write */
+#define	_NSIG	16
 #else
 #define	_NSIG	16
 #endif	/* __USG or __BSD4_2 */
diff --git a/lang/cem/libcc.ansi/headers/stdarg.h b/lang/cem/libcc.ansi/headers/stdarg.h
index b3e30be20..d580a98e8 100644
--- a/lang/cem/libcc.ansi/headers/stdarg.h
+++ b/lang/cem/libcc.ansi/headers/stdarg.h
@@ -14,7 +14,7 @@ typedef	char	*va_list;
 #define __vasz(x)		((sizeof(x)+sizeof(int)-1) & ~(sizeof(int) -1))
 
 #define va_start(ap, parmN)	(ap = (va_list)&parmN + __vasz(parmN))
-#define va_arg(ap, type)	(*((type *)((ap += __vasz(type)) - __vasz(type))))
+#define va_arg(ap, type)	(*((type *)(void *)((ap += __vasz(type)) - __vasz(type))))
 #define va_end(ap)
 
 #endif	/* _STDARG_H */
diff --git a/lang/cem/libcc.ansi/headers/stddef.h b/lang/cem/libcc.ansi/headers/stddef.h
index 8cc619b4a..27ab5fd1c 100644
--- a/lang/cem/libcc.ansi/headers/stddef.h
+++ b/lang/cem/libcc.ansi/headers/stddef.h
@@ -11,7 +11,7 @@
 
 #define	NULL		((void *)0)
 
-#define	offsetof(type, ident)		(((size_t) &(((type *)0)->ident)))
+#define	offsetof(type, ident)		((size_t) &(((type *)0)->ident))
 
 #if	_EM_PSIZE == 2
 typedef int	ptrdiff_t;	/* result of substracting two pointers */