diff --git a/scripts/kconfig/expr.h b/scripts/kconfig/expr.h
index 80fce57080c..d4ecce8bc3a 100644
--- a/scripts/kconfig/expr.h
+++ b/scripts/kconfig/expr.h
@@ -10,6 +10,7 @@
 extern "C" {
 #endif
 
+#include <assert.h>
 #include <stdio.h>
 #ifndef __cplusplus
 #include <stdbool.h>
diff --git a/scripts/kconfig/lkc.h b/scripts/kconfig/lkc.h
index b633bdb9f3d..c18f2bd9c09 100644
--- a/scripts/kconfig/lkc.h
+++ b/scripts/kconfig/lkc.h
@@ -90,8 +90,10 @@ struct conf_printer {
 /* confdata.c and expr.c */
 static inline void xfwrite(const void *str, size_t len, size_t count, FILE *out)
 {
-	if (fwrite(str, len, count, out) < count)
-		fprintf(stderr, "\nError in writing or end of file.\n");
+	assert(len != 0);
+
+	if (fwrite(str, len, count, out) != count)
+		fprintf(stderr, "Error in writing or end of file.\n");
 }
 
 /* menu.c */