diff --git a/src/include/c.h b/src/include/c.h
index 2c2451d11e1..3d047490078 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -104,6 +104,15 @@
  * XLC: https://www.ibm.com/support/knowledgecenter/SSGH2K_13.1.2/com.ibm.xlc131.aix.doc/language_ref/type_attrib.html
  */
 
+/*
+ * For compilers which don't support __has_attribute, we just define
+ * __has_attribute(x) to 0 so that we can define macros for various
+ * __attribute__s more easily below.
+ */
+#ifndef __has_attribute
+#define __has_attribute(attribute) 0
+#endif
+
 /* only GCC supports the unused attribute */
 #ifdef __GNUC__
 #define pg_attribute_unused() __attribute__((unused))
@@ -195,8 +204,6 @@
  * Marking certain functions as "hot" or "cold" can be useful to assist the
  * compiler in arranging the assembly code in a more efficient way.
  */
-#if defined(__has_attribute)
-
 #if __has_attribute (cold)
 #define pg_attribute_cold __attribute__((cold))
 #else
@@ -209,11 +216,6 @@
 #define pg_attribute_hot
 #endif
 
-#else
-#define pg_attribute_hot
-#define pg_attribute_cold
-#endif
-
 /*
  * Mark a point as unreachable in a portable fashion.  This should preferably
  * be something that the compiler understands, to aid code generation.
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index cb7f8c30c30..e8f04a16916 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -160,7 +160,7 @@
 extern bool message_level_is_interesting(int elevel);
 
 extern bool errstart(int elevel, const char *domain);
-extern bool pg_attribute_cold errstart_cold(int elevel, const char *domain);
+extern pg_attribute_cold bool errstart_cold(int elevel, const char *domain);
 extern void errfinish(const char *filename, int lineno, const char *funcname);
 
 extern int	errcode(int sqlerrcode);