diff --git a/js/src/jit-test/tests/ion/bug1000960.js b/js/src/jit-test/tests/ion/bug1000960.js
new file mode 100644
index 000000000000..bf32f844399c
--- /dev/null
+++ b/js/src/jit-test/tests/ion/bug1000960.js
@@ -0,0 +1,9 @@
+function testFloat32SetElemIC(a) {
+  for (var i = 0; i < a.length; i++) {
+    var r = Math.fround(Number.MAX_VALUE);
+    a[i] = r;
+    assertEq(a[i], r);
+  }
+}
+testFloat32SetElemIC(new Array(2048));
+testFloat32SetElemIC(new Float32Array(2048));
diff --git a/js/src/jit/arm/MacroAssembler-arm.h b/js/src/jit/arm/MacroAssembler-arm.h
index fb924993fa7f..0b0fb11b4aad 100644
--- a/js/src/jit/arm/MacroAssembler-arm.h
+++ b/js/src/jit/arm/MacroAssembler-arm.h
@@ -1595,7 +1595,7 @@ class MacroAssemblerARMCompat : public MacroAssemblerARM
     }
 
     void moveFloat32(FloatRegister src, FloatRegister dest) {
-        as_vmov(VFPRegister(src).singleOverlay(), VFPRegister(dest).singleOverlay());
+        as_vmov(VFPRegister(dest).singleOverlay(), VFPRegister(src).singleOverlay());
     }
 
 #ifdef JSGC_GENERATIONAL