diff --git a/src/include/port/pg_bitutils.h b/src/include/port/pg_bitutils.h
index 799f70d052..46bf4f0103 100644
--- a/src/include/port/pg_bitutils.h
+++ b/src/include/port/pg_bitutils.h
@@ -300,8 +300,8 @@ pg_ceil_log2_64(uint64 num)
 
 #ifdef TRY_POPCNT_FAST
 /* Attempt to use the POPCNT instruction, but perform a runtime check first */
-extern int	(*pg_popcount32) (uint32 word);
-extern int	(*pg_popcount64) (uint64 word);
+extern PGDLLIMPORT int (*pg_popcount32) (uint32 word);
+extern PGDLLIMPORT int (*pg_popcount64) (uint64 word);
 
 #else
 /* Use a portable implementation -- no need for a function pointer. */