diff --git a/js/src/vm/Debugger.cpp b/js/src/vm/Debugger.cpp
index e6de5ef1b5..344ee3a4d1 100644
--- a/js/src/vm/Debugger.cpp
+++ b/js/src/vm/Debugger.cpp
@@ -6286,8 +6286,12 @@ Debugger::observesFrame(const FrameIter& iter) const
         if (thisVal.isMagic() && thisVal.whyMagic() == JS_IS_CONSTRUCTING)
             return false;
     }
-    if (iter.isWasm())
+    if (iter.isWasm()) {
+        // Skip frame of wasm instances we cannot observe.
+        if (!iter.wasmDebugEnabled())
+            return false;
         return observesWasm(iter.wasmInstance());
+    }
     return observesScript(iter.script());
 }
 
diff --git a/js/src/vm/Stack.h b/js/src/vm/Stack.h
index 466e9400ba..42faa1158a 100644
--- a/js/src/vm/Stack.h
+++ b/js/src/vm/Stack.h
@@ -1835,6 +1835,8 @@ class FrameIter
     // -----------------------------------------------------------
 	//  The following functions can only be called when isWasm()
     // -----------------------------------------------------------
+
+    inline bool wasmDebugEnabled() const;
     inline wasm::Instance* wasmInstance() const;
 
     // -----------------------------------------------------------
@@ -2083,11 +2085,19 @@ FrameIter::script() const
     return data_.jitFrames_.script();
 }
 
+inline bool
+FrameIter::wasmDebugEnabled() const
+{
+    MOZ_ASSERT(!done());
+    MOZ_ASSERT(data_.state_ == WASM);
+    return data_.wasmFrames_.debugEnabled();
+}
+
 inline wasm::Instance*
 FrameIter::wasmInstance() const
 {
     MOZ_ASSERT(!done());
-    MOZ_ASSERT(data_.state_ == WASM);
+    MOZ_ASSERT(data_.state_ == WASM && wasmDebugEnabled());
     return data_.wasmFrames_.instance();
 }