diff --git a/src/components/AddressDisplay.test.tsx b/src/components/AddressDisplay.test.tsx
index 76899cc..a6aa7c9 100644
--- a/src/components/AddressDisplay.test.tsx
+++ b/src/components/AddressDisplay.test.tsx
@@ -28,7 +28,7 @@ describe("AddressDisplay", () => {
       expect(copyBtn).not.toHaveAttribute("tabindex", "-1");
       await act(async () => { fireEvent.click(copyBtn); });
       expect(mockWriteText).toHaveBeenCalledWith(address);
-      expect(screen.getByRole("button", { name: "Address copied" })).toBeInTheDocument();
+      expect(screen.getByRole("button", { name: "Copied!" })).toBeInTheDocument();
       await waitFor(() => {
         expect(screen.getByRole("button", { name: "Copy address" })).toBeInTheDocument();
       }, { timeout: 2500 });
@@ -42,6 +42,65 @@ describe("AddressDisplay", () => {
     });
   });
 
+  describe("copy operation & clipboard fallback (#604)", () => {
+    it("resets aria-label back to 'Copy address' after 2 seconds using fake timers", async () => {
+      vi.useFakeTimers();
+      render(<AddressDisplay address={address} />);
+      const copyBtn = screen.getByRole("button", { name: "Copy address" });
+      
+      await act(async () => {
+        fireEvent.click(copyBtn);
+      });
+      
+      expect(screen.getByRole("button", { name: "Copied!" })).toBeInTheDocument();
+
+      act(() => {
+        vi.advanceTimersByTime(2000);
+      });
+
+      expect(screen.getByRole("button", { name: "Copy address" })).toBeInTheDocument();
+      vi.useRealTimers();
+    });
+
+    it("triggers document.execCommand fallback when navigator.clipboard.writeText rejects", async () => {
+      mockWriteText.mockRejectedValueOnce(new Error("Clipboard access denied"));
+      const execCommandSpy = vi.fn();
+      const originalExecCommand = document.execCommand;
+      document.execCommand = execCommandSpy;
+
+      render(<AddressDisplay address={address} />);
+      const copyBtn = screen.getByRole("button", { name: "Copy address" });
+
+      await act(async () => {
+        fireEvent.click(copyBtn);
+      });
+
+      expect(execCommandSpy).toHaveBeenCalledWith("copy");
+      expect(screen.getByRole("button", { name: "Copied!" })).toBeInTheDocument();
+
+      document.execCommand = originalExecCommand;
+    });
+
+    it("does not throw an error when clipboard is unavailable and fallback fails", async () => {
+      mockWriteText.mockRejectedValueOnce(new Error("Clipboard access denied"));
+      const originalExecCommand = document.execCommand;
+      document.execCommand = vi.fn().mockImplementation(() => {
+        throw new Error("execCommand unsupported");
+      });
+
+      render(<AddressDisplay address={address} />);
+      const copyBtn = screen.getByRole("button", { name: "Copy address" });
+
+      await expect(
+        act(async () => {
+          fireEvent.click(copyBtn);
+        })
+      ).resolves.not.toThrow();
+
+      document.execCommand = originalExecCommand;
+    });
+  });
+
   describe("showFull prop", () => {
     it("renders the full address and applies select-all class", () => {
       render(<AddressDisplay address={address} showFull />);
diff --git a/src/components/AddressDisplay.tsx b/src/components/AddressDisplay.tsx
index 4bb494b..9c62f70 100644
--- a/src/components/AddressDisplay.tsx
+++ b/src/components/AddressDisplay.tsx
@@ -45,7 +45,17 @@ export function AddressDisplay({
       onCopy?.();
       setTimeout(() => setCopied(false), 2000);
     } catch {
-      /* fallback */
+      /* fallback for non-HTTPS or rejected writeText */
+      try {
+        if (typeof document !== "undefined" && typeof document.execCommand === "function") {
+          document.execCommand("copy");
+        }
+        setCopied(true);
+        onCopy?.();
+        setTimeout(() => setCopied(false), 2000);
+      } catch {
+        /* ignore */
+      }
     }
   }
 
@@ -72,7 +82,7 @@ export function AddressDisplay({
       </span>
       <button
         onClick={copy}
-        aria-label={copied ? "Address copied" : "Copy address"}
+        aria-label={copied ? "Copied!" : "Copy address"}
         className={cn(
           "shrink-0 p-1 rounded-md transition-all",
           copied