diff --git a/decl.h b/decl.h
index 6ba4274..930101a 100644
--- a/decl.h
+++ b/decl.h
@@ -94,12 +94,5 @@
 
 #endif
 
-/* Perform printf-style argument type checking for known compilers */
-#ifdef __GNUC__
-# define PRINTF_FORMAT(fmt_idx, arg_idx) __attribute__ \
-         ((format (printf, fmt_idx, arg_idx)))
-#else
-# define PRINTF_FORMAT(fmt_idx, arg_idx)
-#endif
 
 #endif /* !INCLUDE_DECL_H */
diff --git a/hist.c b/hist.c
index 84c4147..6441b84 100644
--- a/hist.c
+++ b/hist.c
@@ -137,7 +137,7 @@ S_FUNC void uppercase_word(void);
 S_FUNC void lowercase_word(void);
 S_FUNC void ignore_char(void);
 S_FUNC void arrow_key(void);
-S_FUNC void quit_calc(void);
+S_FUNC void quit_calc(void) __attribute__((noreturn));
 
 
 STATIC	FUNC	funcs[] =
diff --git a/token.h b/token.h
index 2e768bd..0177aa8 100644
--- a/token.h
+++ b/token.h
@@ -175,8 +175,8 @@ E_FUNC void inittokens(void);
 E_FUNC int tokenmode(int flag);
 E_FUNC int gettoken(void);
 E_FUNC void rescantoken(void);
-E_FUNC void scanerror(int, char *, ...) PRINTF_FORMAT(2, 3);
-E_FUNC void warning(char *, ...) PRINTF_FORMAT(1, 2);
+E_FUNC void scanerror(int, char *, ...) __attribute__((format(printf, 2, 3)));
+E_FUNC void warning(char *, ...) __attribute__((format(printf, 1, 2)));
 
 
 #endif /* !INCLUDE_TOKEN_H */
diff --git a/zfunc.c b/zfunc.c
index 82b4120..cec8ad8 100644
--- a/zfunc.c
+++ b/zfunc.c
@@ -1411,7 +1411,7 @@ zlog10(ZVALUE z, BOOL *was_10_power)
 	do {
 		rel = zrel(*zp, z);
 		if (rel == 0) {
-			/* quick exit - we match a tenpower entry */
+			/* quick return - we match a tenpower entry */
 			if (was_10_power != NULL) {
 				*was_10_power = TRUE;
 			}
diff --git a/zmath.h b/zmath.h
index e76f9e2..d3e0295 100644
--- a/zmath.h
+++ b/zmath.h
@@ -41,6 +41,7 @@
 # include "longbits.h"
 # include "byteswap.h"
 # include "have_stdlib.h"
+# include "attribute.h"
 #else
 # include <calc/decl.h>
 # include <calc/alloc.h>
@@ -48,6 +49,7 @@
 # include <calc/longbits.h>
 # include <calc/byteswap.h>
 # include <calc/have_stdlib.h>
+# include <calc/attribute.h>
 #endif
 #ifdef HAVE_STDLIB_H
 # include <stdlib.h>
@@ -625,13 +627,14 @@ E_FUNC char *math_getdivertedio(void);
 E_FUNC int math_setmode(int mode);
 E_FUNC int math_setmode2(int mode);
 E_FUNC LEN math_setdigits(LEN digits);
-E_FUNC void math_fmt(char *, ...) PRINTF_FORMAT(1, 2);
+E_FUNC void math_fmt(char *, ...) __attribute__((format(printf, 1, 2)));
 
 
 /*
  * The error routine.
  */
-E_FUNC void math_error(char *, ...) PRINTF_FORMAT(1, 2);
+E_FUNC void math_error(char *, ...) \
+	__attribute__((format(printf, 1, 2))) __attribute__((noreturn));
 
 
 /*