diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index e9f542cfedd..d14ea851847 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -2649,10 +2649,11 @@ static struct config_int ConfigureNamesInt[] =
 		},
 		&effective_io_concurrency,
 #ifdef USE_PREFETCH
-		1, 0, MAX_IO_CONCURRENCY,
+		1,
 #else
-		0, 0, 0,
+		0,
 #endif
+		0, MAX_IO_CONCURRENCY,
 		check_effective_io_concurrency, assign_effective_io_concurrency, NULL
 	},
 
@@ -10709,6 +10710,11 @@ check_effective_io_concurrency(int *newval, void **extra, GucSource source)
 	else
 		return false;
 #else
+	if (*newval != 0)
+	{
+		GUC_check_errdetail("effective_io_concurrency must be set to 0 on platforms that lack posix_fadvise()");
+		return false;
+	}
 	return true;
 #endif							/* USE_PREFETCH */
 }
diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index b0365254f65..cc5eedfc41d 100644
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -136,7 +136,9 @@
 /*
  * USE_PREFETCH code should be compiled only if we have a way to implement
  * prefetching.  (This is decoupled from USE_POSIX_FADVISE because there
- * might in future be support for alternative low-level prefetch APIs.)
+ * might in future be support for alternative low-level prefetch APIs.
+ * If you change this, you probably need to adjust the error message in
+ * check_effective_io_concurrency.)
  */
 #ifdef USE_POSIX_FADVISE
 #define USE_PREFETCH