diff --git a/core/c/libc/stdatomic.odin b/core/c/libc/stdatomic.odin
index a5dd78afc..26ea0db5e 100644
--- a/core/c/libc/stdatomic.odin
+++ b/core/c/libc/stdatomic.odin
@@ -47,9 +47,9 @@ kill_dependency :: #force_inline proc(value: $T) -> T {
 
 // 7.17.4 Fences
 atomic_thread_fence :: #force_inline proc(order: memory_order) {
-	switch order {
-	case .relaxed: intrinsics.atomic_thread_fence(.relaxed)
-	case .consume: intrinsics.atomic_thread_fence(.consume)
+	assert(order != .relaxed)
+	assert(order != .consume)
+	#partial switch order {
 	case .acquire: intrinsics.atomic_thread_fence(.acquire)
 	case .release: intrinsics.atomic_thread_fence(.release)
 	case .acq_rel: intrinsics.atomic_thread_fence(.acq_rel)
@@ -58,9 +58,9 @@ atomic_thread_fence :: #force_inline proc(order: memory_order) {
 }
 
 atomic_signal_fence :: #force_inline proc(order: memory_order) {
-	switch order {
-	case .relaxed: intrinsics.atomic_signal_fence(.relaxed)
-	case .consume: intrinsics.atomic_signal_fence(.consume)
+	assert(order != .relaxed)
+	assert(order != .consume)
+	#partial switch order {
 	case .acquire: intrinsics.atomic_signal_fence(.acquire)
 	case .release: intrinsics.atomic_signal_fence(.release)
 	case .acq_rel: intrinsics.atomic_signal_fence(.acq_rel)
diff --git a/src/check_builtin.cpp b/src/check_builtin.cpp
index a82577b31..8b8814176 100644
--- a/src/check_builtin.cpp
+++ b/src/check_builtin.cpp
@@ -3235,10 +3235,24 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 
 	case BuiltinProc_atomic_thread_fence:
 	case BuiltinProc_atomic_signal_fence:
-		if (!check_atomic_memory_order_argument(c, ce->args[0], builtin_name, nullptr)) {
-			return false;
+		{
+			OdinAtomicMemoryOrder memory_order = {};
+			if (!check_atomic_memory_order_argument(c, ce->args[0], builtin_name, &memory_order)) {
+				return false;
+			}
+			switch (memory_order) {
+			case OdinAtomicMemoryOrder_acquire:
+			case OdinAtomicMemoryOrder_release:
+			case OdinAtomicMemoryOrder_acq_rel:
+			case OdinAtomicMemoryOrder_seq_cst:
+				break;
+			default:
+				error(ce->args[0], "Illegal memory ordering for '%.*s', got .%s", LIT(builtin_name), OdinAtomicMemoryOrder_strings[memory_order]);
+				break;
+			}
+
+			operand->mode = Addressing_NoValue;
 		}
-		operand->mode = Addressing_NoValue;
 		break;
 
 	case BuiltinProc_volatile_store:
@@ -3280,7 +3294,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 			case OdinAtomicMemoryOrder_consume:
 			case OdinAtomicMemoryOrder_acquire:
 			case OdinAtomicMemoryOrder_acq_rel:
-				error(ce->args[2], "Illegal memory order .%s for %.*s", OdinAtomicMemoryOrder_strings[memory_order], LIT(builtin_name));
+				error(ce->args[2], "Illegal memory order .%s for '%.*s'", OdinAtomicMemoryOrder_strings[memory_order], LIT(builtin_name));
 				break;
 			}
 
@@ -3322,7 +3336,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 			switch (memory_order) {
 			case OdinAtomicMemoryOrder_release:
 			case OdinAtomicMemoryOrder_acq_rel:
-				error(ce->args[1], "Illegal memory order .%s for %.*s", OdinAtomicMemoryOrder_strings[memory_order], LIT(builtin_name));
+				error(ce->args[1], "Illegal memory order .%s for '%.*s'", OdinAtomicMemoryOrder_strings[memory_order], LIT(builtin_name));
 				break;
 			}
 
@@ -3474,7 +3488,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 
 
 			if (invalid_combination) {
-				error(ce->args[3], "Illegal memory order pairing for %.*s, success = .%s, failure = .%s",
+				error(ce->args[3], "Illegal memory order pairing for '%.*s', success = .%s, failure = .%s",
 					LIT(builtin_name),
 					OdinAtomicMemoryOrder_strings[success_memory_order],
 					OdinAtomicMemoryOrder_strings[failure_memory_order]