diff --git a/include/misc.h b/include/misc.h
index cce94dfc..29a3671c 100644
--- a/include/misc.h
+++ b/include/misc.h
@@ -75,6 +75,13 @@
 extern void oops(char *, char *, int);
 extern void (*oops_handler)(void);
 
+/*
+ * Assert constant expression @cond, return 1.
+ * If @cond is zero, force a compilation error.
+ */
+#define BUILD_ASSERT_ONE(cond) \
+    (sizeof(char[1 - 2 * !(cond)]))
+
 void exit_nomem(void) ATTRIBUTE((noreturn));
 
 	/* return codes from command routines */
diff --git a/include/nsc.h b/include/nsc.h
index c3e39277..4797bcd3 100644
--- a/include/nsc.h
+++ b/include/nsc.h
@@ -67,12 +67,14 @@ enum nsc_type {
 #define NSC_IS_PROMOTED(type) (NSC_LONG <= (type) && (type) <= NSC_STRING)
 
 /* Return nsc_type for a signed integer with the same size as TYPE. */
-#define NSC_SITYPE(type)				\
+#define NSC_SITYPE(type) \
+    (BUILD_ASSERT_ONE(NSC_SITYPE_(type) != NSC_NOTYPE) * NSC_SITYPE_(type))
+#define NSC_SITYPE_(type)				\
     (sizeof(type) == 1 ? NSC_CHAR			\
      : sizeof(type) == sizeof(short) ? NSC_SHORT	\
      : sizeof(type) == sizeof(int) ? NSC_INT		\
      : sizeof(type) == sizeof(long) ? NSC_LONG		\
-     : 1/0)
+     : NSC_NOTYPE)
 
 /* Value category */
 enum nsc_cat {