diff --git a/include/extern.h b/include/extern.h
index d60e45f64..277837afb 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -2055,7 +2055,7 @@ extern void msmsg(const char *, ...) PRINTF_F(1, 2);
 extern void gettty(void);
 extern void settty(const char *);
 extern void setftty(void);
-extern void error(const char *, ...) PRINTF_F(1, 2);
+extern void error(const char *, ...) PRINTF_F(1, 2) NORETURN;
 #if defined(TIMED_DELAY) && defined(_MSC_VER)
 extern void msleep(unsigned);
 #endif
@@ -2969,7 +2969,7 @@ extern void settty(const char *);
 extern void setftty(void);
 extern void intron(void);
 extern void introff(void);
-extern void error (const char *, ...) PRINTF_F(1, 2);
+extern void error (const char *, ...) PRINTF_F(1, 2) NORETURN;
 #ifdef ENHANCED_SYMBOLS
 extern void tty_utf8graphics_fixup(void);
 #endif
@@ -3136,7 +3136,7 @@ extern void shuttty(const char *);
 extern void setftty(void);
 extern void intron(void);
 extern void introff(void);
-extern void error (const char *, ...) PRINTF_F(1, 2);
+extern void error (const char *, ...) PRINTF_F(1, 2) NORETURN;
 #ifdef TIMED_DELAY
 extern void msleep(unsigned);
 #endif