diff --git a/src/compiler/sema_decls.c b/src/compiler/sema_decls.c
index 2cf62f02c..281f45fb4 100644
--- a/src/compiler/sema_decls.c
+++ b/src/compiler/sema_decls.c
@@ -3181,7 +3181,6 @@ static bool sema_analyse_attribute(SemaContext *context, ResolvedAttrData *attr_
 		RETURN_SEMA_ERROR(attr, "'%s' is not a valid %s attribute.", attr->name, attribute_domain_to_string(domain));
 	}
 
-	// No attribute has more than one argument right now.
 	unsigned args = vec_size(attr->exprs);
 	if (args > 1 && type != ATTRIBUTE_LINK && type != ATTRIBUTE_TAG && type != ATTRIBUTE_WASM)
 	{
@@ -3507,8 +3506,11 @@ static bool sema_analyse_attribute(SemaContext *context, ResolvedAttrData *attr_
 			}
 			return true;
 		case ATTRIBUTE_NOINLINE:
+			if (decl->func_decl.attr_inline)
+			{
+				RETURN_SEMA_ERROR(attr, "@noinline cannot be combined with @inline.");
+			}
 			decl->func_decl.attr_noinline = true;
-			decl->func_decl.attr_inline = false;
 			break;
 		case ATTRIBUTE_NOPADDING:
 			decl->attr_nopadding = true;
@@ -3527,7 +3529,7 @@ static bool sema_analyse_attribute(SemaContext *context, ResolvedAttrData *attr_
 			decl->func_decl.signature.attrs.always_const = true;
 			break;
 		case ATTRIBUTE_NODISCARD:
-			if (decl->func_decl.signature.attrs.nodiscard)
+			if (decl->func_decl.signature.attrs.noreturn)
 			{
 				RETURN_SEMA_ERROR(attr, "@nodiscard cannot be combined with @noreturn.");
 			}
@@ -3537,8 +3539,11 @@ static bool sema_analyse_attribute(SemaContext *context, ResolvedAttrData *attr_
 			decl->func_decl.signature.attrs.maydiscard = true;
 			break;
 		case ATTRIBUTE_INLINE:
+			if (decl->func_decl.attr_noinline)
+			{
+				RETURN_SEMA_ERROR(attr, "@inline cannot be combined with @noinline.");
+			}
 			decl->func_decl.attr_inline = true;
-			decl->func_decl.attr_noinline = false;
 			break;
 		case ATTRIBUTE_NORETURN:
 			if (decl->func_decl.signature.attrs.nodiscard)
@@ -3616,9 +3621,17 @@ static bool sema_analyse_attribute(SemaContext *context, ResolvedAttrData *attr_
 			decl->is_packed = true;
 			break;
 		case ATTRIBUTE_UNUSED:
+			if(decl->is_must_use)
+			{
+				RETURN_SEMA_ERROR(attr, "@unused cannot be combined with @used.");
+			}
 			decl->is_maybe_unused = true;
 			break;
 		case ATTRIBUTE_USED:
+			if(decl->is_maybe_unused)
+			{
+				RETURN_SEMA_ERROR(attr, "@used cannot be combined with @unused.");
+			}
 			decl->is_must_use = true;
 			break;
 		case ATTRIBUTE_PURE:
diff --git a/test/test_suite/attributes/bad_combinations.c3 b/test/test_suite/attributes/bad_combinations.c3
new file mode 100644
index 000000000..9fd1ea8fc
--- /dev/null
+++ b/test/test_suite/attributes/bad_combinations.c3
@@ -0,0 +1,9 @@
+module test;
+fn void foo() @inline @noinline // #error: cannot be combined
+{}
+
+fn void bar() @used @unused // #error: cannot be combined
+{}
+
+fn bool baz() @nodiscard @noreturn // #error: cannot be combined
+{}