diff --git a/recipes-devtools/rust/rust.inc b/recipes-devtools/rust/rust.inc
index 06c35de..ea2e11a 100644
--- a/recipes-devtools/rust/rust.inc
+++ b/recipes-devtools/rust/rust.inc
@@ -78,10 +78,11 @@ def llvm_features_from_tune(d):
     if 'dsp' in feat:
         f.append("+dsp")
 
-    if d.getVar('ARM_THUMB_OPT') is "thumb":
-        if not feat.isdisjoint(v7):
-            f.append("+thumb2")
-        f.append("+thumb-mode")
+    if 'thumb' in feat:
+        if d.getVar('ARM_THUMB_OPT') is "thumb":
+            if not feat.isdisjoint(v7):
+                f.append("+thumb2")
+            f.append("+thumb-mode")
 
     if 'cortexa5' in feat:
         f.append("+a5")