diff --git a/src/interfaces/ecpg/preproc/output.c b/src/interfaces/ecpg/preproc/output.c
index 59d5d30df4a..93a1ad1498d 100644
--- a/src/interfaces/ecpg/preproc/output.c
+++ b/src/interfaces/ecpg/preproc/output.c
@@ -155,6 +155,7 @@ output_statement(char *stmt, int whenever_mode, enum ECPG_statement_type st)
 	free(stmt);
 	if (connection != NULL)
 		free(connection);
+	connection = NULL;
 }
 
 void
@@ -169,6 +170,7 @@ output_prepare_statement(char *name, char *stmt)
 	free(name);
 	if (connection != NULL)
 		free(connection);
+	connection = NULL;
 }
 
 void
@@ -189,6 +191,7 @@ output_deallocate_prepare_statement(char *name)
 	free(name);
 	if (connection != NULL)
 		free(connection);
+	connection = NULL;
 }
 
 static void