diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index c51e3afdb4..8949684afe 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -271,6 +271,11 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("nondeterministic collations not supported with this provider")));
 
+		if (collicurules && collprovider != COLLPROVIDER_ICU)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+					 errmsg("ICU rules cannot be specified unless locale provider is ICU")));
+
 		if (collprovider == COLLPROVIDER_ICU)
 		{
 #ifdef USE_ICU
diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 7063a5a7ed..4d5d5d6866 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1066,6 +1066,11 @@ createdb(ParseState *pstate, const CreatedbStmt *stmt)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 					 errmsg("ICU locale cannot be specified unless locale provider is ICU")));
+
+		if (dbicurules)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+					 errmsg("ICU rules cannot be specified unless locale provider is ICU")));
 	}
 
 	/*