diff --git a/js/src/ctypes/CTypes.cpp b/js/src/ctypes/CTypes.cpp
index 552602aa1eb8..a376f9963945 100644
--- a/js/src/ctypes/CTypes.cpp
+++ b/js/src/ctypes/CTypes.cpp
@@ -1494,6 +1494,40 @@ IncompatibleThisType(JSContext* cx, const char* funName, const char* actualType,
   return false;
 }
 
+static bool
+InvalidIndexError(JSContext* cx, HandleValue val)
+{
+  JSAutoByteString idBytes;
+  const char* indexStr = CTypesToSourceForError(cx, val, idBytes);
+  if (!indexStr)
+    return false;
+
+  JS_ReportErrorNumber(cx, GetErrorMessage, nullptr,
+                       CTYPESMSG_INVALID_INDEX, indexStr);
+  return false;
+}
+
+static bool
+InvalidIndexError(JSContext* cx, HandleId id)
+{
+  RootedValue idVal(cx, IdToValue(id));
+  return InvalidIndexError(cx, idVal);
+}
+
+static bool
+InvalidIndexRangeError(JSContext* cx, size_t index, size_t length)
+{
+  char indexStr[16];
+  JS_snprintf(indexStr, 16, "%u", index);
+
+  char lengthStr[16];
+  JS_snprintf(lengthStr, 16, "%u", length);
+
+  JS_ReportErrorNumber(cx, GetErrorMessage, nullptr,
+                       CTYPESMSG_INVALID_RANGE, indexStr, lengthStr);
+  return false;
+}
+
 static bool
 NonPrimitiveError(JSContext* cx, HandleObject typeObj)
 {
@@ -5376,9 +5410,11 @@ ArrayType::Getter(JSContext* cx, HandleObject obj, HandleId idval, MutableHandle
     // Chances are it's a regular property lookup, so return.
     return true;
   }
-  if (!ok || index >= length) {
-    JS_ReportError(cx, "invalid index");
-    return false;
+  if (!ok) {
+    return InvalidIndexError(cx, idval);
+  }
+  if (index >= length) {
+    return InvalidIndexRangeError(cx, index, length);
   }
 
   RootedObject baseType(cx, GetBaseType(typeObj));
@@ -5417,9 +5453,11 @@ ArrayType::Setter(JSContext* cx, HandleObject obj, HandleId idval, MutableHandle
     // Chances are it's a regular property lookup, so return.
     return result.succeed();
   }
-  if (!ok || index >= length) {
-    JS_ReportError(cx, "invalid index");
-    return false;
+  if (!ok) {
+    return InvalidIndexError(cx, idval);
+  }
+  if (index >= length) {
+    return InvalidIndexRangeError(cx, index, length);
   }
 
   RootedObject baseType(cx, GetBaseType(typeObj));
@@ -5469,10 +5507,11 @@ ArrayType::AddressOfElement(JSContext* cx, unsigned argc, Value* vp)
   // Convert the index to a size_t and bounds-check it.
   size_t index;
   size_t length = GetLength(typeObj);
-  if (!jsvalToSize(cx, args[0], false, &index) ||
-      index >= length) {
-    JS_ReportError(cx, "invalid index");
-    return false;
+  if (!jsvalToSize(cx, args[0], false, &index)) {
+    return InvalidIndexError(cx, args[0]);
+  }
+  if (index >= length) {
+    return InvalidIndexRangeError(cx, index, length);
   }
 
   // Manually set the pointer inside the object, so we skip the conversion step.
diff --git a/js/src/ctypes/ctypes.msg b/js/src/ctypes/ctypes.msg
index bac1431d367f..86b50893971c 100644
--- a/js/src/ctypes/ctypes.msg
+++ b/js/src/ctypes/ctypes.msg
@@ -24,6 +24,8 @@ MSG_DEF(CTYPESMSG_TYPE_ERROR,    2, JSEXN_TYPEERR, "expected {0}, got {1}")
 /* array */
 MSG_DEF(CTYPESMSG_ARRAY_MISMATCH,4, JSEXN_TYPEERR, "length of {0} does not match to the length of the type {1} (expected {2}, got {3})")
 MSG_DEF(CTYPESMSG_ARRAY_OVERFLOW,4, JSEXN_TYPEERR, "length of {0} does not fit in the length of the type {1} (expected {2} or lower, got {3})")
+MSG_DEF(CTYPESMSG_INVALID_INDEX, 1, JSEXN_TYPEERR, "{0} is not a valid array index")
+MSG_DEF(CTYPESMSG_INVALID_RANGE, 2, JSEXN_RANGEERR, "array index {0} is out of bounds for array of length {1}")
 
 /* struct */
 MSG_DEF(CTYPESMSG_FIELD_MISMATCH,5, JSEXN_TYPEERR, "property count of {0} does not match to field count of the type {1} (expected {2}, got {3}){4}")
diff --git a/js/src/jit-test/tests/ctypes/array-index.js b/js/src/jit-test/tests/ctypes/array-index.js
new file mode 100644
index 000000000000..e70add1a062d
--- /dev/null
+++ b/js/src/jit-test/tests/ctypes/array-index.js
@@ -0,0 +1,29 @@
+load(libdir + 'asserts.js');
+
+function test() {
+  let a = ctypes.int32_t.array(10)();
+  assertTypeErrorMessage(() => { let x = a[-1]; },
+                          "the string \"-1\" is not a valid array index");
+  assertTypeErrorMessage(() => { a[-1] = 1; },
+                          "the string \"-1\" is not a valid array index");
+  assertTypeErrorMessage(() => { a.addressOfElement(-1); },
+                          "the number -1 is not a valid array index");
+
+  assertRangeErrorMessage(() => { let x = a[10]; },
+                          "array index 10 is out of bounds for array of length 10");
+  assertRangeErrorMessage(() => { a[10] = 1; },
+                          "array index 10 is out of bounds for array of length 10");
+  assertRangeErrorMessage(() => { a.addressOfElement(10); },
+                          "array index 10 is out of bounds for array of length 10");
+
+  let obj = {
+    toSource() {
+      throw 1;
+    }
+  };
+  assertTypeErrorMessage(() => { a.addressOfElement(obj); },
+                          "<<error converting value to string>> is not a valid array index");
+}
+
+if (typeof ctypes === "object")
+  test();
diff --git a/toolkit/components/ctypes/tests/unit/test_jsctypes.js b/toolkit/components/ctypes/tests/unit/test_jsctypes.js
index a4dbb97eaf9d..67f28b619046 100644
--- a/toolkit/components/ctypes/tests/unit/test_jsctypes.js
+++ b/toolkit/components/ctypes/tests/unit/test_jsctypes.js
@@ -2016,9 +2016,9 @@ function run_ArrayType_tests() {
   a[0] = g;
   do_check_eq(a[0].a, 1);
   do_check_eq(a[0].b, 2);
-  do_check_throws(function() { a[-1]; }, Error);
+  do_check_throws(function() { a[-1]; }, TypeError);
   do_check_eq(a[9].a, 0);
-  do_check_throws(function() { a[10]; }, Error);
+  do_check_throws(function() { a[10]; }, RangeError);
 
   do_check_eq(a[ctypes.Int64(0)].a, 1);
   do_check_eq(a[ctypes.UInt64(0)].b, 2);