diff --git a/src/include/c.h b/src/include/c.h
index 82f8e9d4c7..98e3bbf386 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -171,13 +171,19 @@
 #define PG_USED_FOR_ASSERTS_ONLY pg_attribute_unused()
 #endif
 
-/* GCC and XLC support format attributes */
+/*
+ * GCC and XLC support format attributes.  Use pg_attribute_printf()
+ * for our src/port/snprintf.c implementation and functions based on it.
+ * Use pg_attribute_std_printf() for functions based on libc's printf.
+ */
 #if defined(__GNUC__) || defined(__IBMC__)
 #define pg_attribute_format_arg(a) __attribute__((format_arg(a)))
 #define pg_attribute_printf(f,a) __attribute__((format(PG_PRINTF_ATTRIBUTE, f, a)))
+#define pg_attribute_std_printf(f,a) __attribute__((format(printf, f, a)))
 #else
 #define pg_attribute_format_arg(a)
 #define pg_attribute_printf(f,a)
+#define pg_attribute_std_printf(f,a)
 #endif
 
 /* GCC, Sunpro and XLC support aligned, packed and noreturn */
diff --git a/src/interfaces/ecpg/include/pgtypes_format.h b/src/interfaces/ecpg/include/pgtypes_format.h
index d6dd06d361..87160fab59 100644
--- a/src/interfaces/ecpg/include/pgtypes_format.h
+++ b/src/interfaces/ecpg/include/pgtypes_format.h
@@ -20,7 +20,7 @@ extern int PGTYPESbegin_clocale(locale_t *old_locale);
 extern void PGTYPESend_clocale(locale_t old_locale);
 
 extern double PGTYPESstrtod(const char *str, char **endptr);
-extern int PGTYPESsprintf(char *str, const char *format, ...) pg_attribute_printf(2, 3);
-extern int PGTYPESsnprintf(char *str, size_t size, const char *format, ...) pg_attribute_printf(3, 4);
+extern int PGTYPESsprintf(char *str, const char *format, ...) pg_attribute_std_printf(2, 3);
+extern int PGTYPESsnprintf(char *str, size_t size, const char *format, ...) pg_attribute_std_printf(3, 4);
 
 #endif