diff --git a/src/firebird_fdw.h b/src/firebird_fdw.h
index 567b06e..a9957bb 100644
--- a/src/firebird_fdw.h
+++ b/src/firebird_fdw.h
@@ -63,7 +63,7 @@
 							 || (x) == NUMERICOID || (x) == DATEOID || (x) == TIMESTAMPOID \
 							 || (x) == TIMEOID)
 
-union opttype {
+typedef union opttype {
 	char **strptr;
 	int *intptr;
 	bool *boolptr;