diff --git a/javascript/ql/src/semmle/javascript/frameworks/LodashUnderscore.qll b/javascript/ql/src/semmle/javascript/frameworks/LodashUnderscore.qll
index 7ab3e2f8d20b..97bfeea16818 100644
--- a/javascript/ql/src/semmle/javascript/frameworks/LodashUnderscore.qll
+++ b/javascript/ql/src/semmle/javascript/frameworks/LodashUnderscore.qll
@@ -21,10 +21,14 @@ module LodashUnderscore {
     string name;
 
     DefaultMember() {
-      this = DataFlow::moduleMember("underscore", name) or
-      this = DataFlow::moduleMember("lodash", name) or
-      this = DataFlow::moduleImport("lodash/" + name) or
-      this = DataFlow::moduleImport("lodash." + name) or
+      this = DataFlow::moduleMember("underscore", name)
+      or
+      this = DataFlow::moduleMember("lodash", name)
+      or
+      this = DataFlow::moduleImport("lodash/" + name)
+      or
+      this = DataFlow::moduleImport("lodash." + name.toLowerCase()) and isLodashMember(name)
+      or
       this = DataFlow::globalVarRef("_").getAPropertyRead(name)
     }
 
@@ -38,6 +42,319 @@ module LodashUnderscore {
    * In addition, the global variable `_` is assumed to refer to `lodash` or `underscore`.
    */
   DataFlow::SourceNode member(string name) { result.(Member).getName() = name }
+
+  /**
+   * Holds if `name` is the name of a member exported from the `lodash` package
+   * which has a corresponding `lodash.xxx` NPM package.
+   */
+  private predicate isLodashMember(string name) { // Can be generated using Object.keys(require('lodash'))
+    name = "templateSettings" or
+    name = "after" or
+    name = "ary" or
+    name = "assign" or
+    name = "assignIn" or
+    name = "assignInWith" or
+    name = "assignWith" or
+    name = "at" or
+    name = "before" or
+    name = "bind" or
+    name = "bindAll" or
+    name = "bindKey" or
+    name = "castArray" or
+    name = "chain" or
+    name = "chunk" or
+    name = "compact" or
+    name = "concat" or
+    name = "cond" or
+    name = "conforms" or
+    name = "constant" or
+    name = "countBy" or
+    name = "create" or
+    name = "curry" or
+    name = "curryRight" or
+    name = "debounce" or
+    name = "defaults" or
+    name = "defaultsDeep" or
+    name = "defer" or
+    name = "delay" or
+    name = "difference" or
+    name = "differenceBy" or
+    name = "differenceWith" or
+    name = "drop" or
+    name = "dropRight" or
+    name = "dropRightWhile" or
+    name = "dropWhile" or
+    name = "fill" or
+    name = "filter" or
+    name = "flatMap" or
+    name = "flatMapDeep" or
+    name = "flatMapDepth" or
+    name = "flatten" or
+    name = "flattenDeep" or
+    name = "flattenDepth" or
+    name = "flip" or
+    name = "flow" or
+    name = "flowRight" or
+    name = "fromPairs" or
+    name = "functions" or
+    name = "functionsIn" or
+    name = "groupBy" or
+    name = "initial" or
+    name = "intersection" or
+    name = "intersectionBy" or
+    name = "intersectionWith" or
+    name = "invert" or
+    name = "invertBy" or
+    name = "invokeMap" or
+    name = "iteratee" or
+    name = "keyBy" or
+    name = "keys" or
+    name = "keysIn" or
+    name = "map" or
+    name = "mapKeys" or
+    name = "mapValues" or
+    name = "matches" or
+    name = "matchesProperty" or
+    name = "memoize" or
+    name = "merge" or
+    name = "mergeWith" or
+    name = "method" or
+    name = "methodOf" or
+    name = "mixin" or
+    name = "negate" or
+    name = "nthArg" or
+    name = "omit" or
+    name = "omitBy" or
+    name = "once" or
+    name = "orderBy" or
+    name = "over" or
+    name = "overArgs" or
+    name = "overEvery" or
+    name = "overSome" or
+    name = "partial" or
+    name = "partialRight" or
+    name = "partition" or
+    name = "pick" or
+    name = "pickBy" or
+    name = "property" or
+    name = "propertyOf" or
+    name = "pull" or
+    name = "pullAll" or
+    name = "pullAllBy" or
+    name = "pullAllWith" or
+    name = "pullAt" or
+    name = "range" or
+    name = "rangeRight" or
+    name = "rearg" or
+    name = "reject" or
+    name = "remove" or
+    name = "rest" or
+    name = "reverse" or
+    name = "sampleSize" or
+    name = "set" or
+    name = "setWith" or
+    name = "shuffle" or
+    name = "slice" or
+    name = "sortBy" or
+    name = "sortedUniq" or
+    name = "sortedUniqBy" or
+    name = "split" or
+    name = "spread" or
+    name = "tail" or
+    name = "take" or
+    name = "takeRight" or
+    name = "takeRightWhile" or
+    name = "takeWhile" or
+    name = "tap" or
+    name = "throttle" or
+    name = "thru" or
+    name = "toArray" or
+    name = "toPairs" or
+    name = "toPairsIn" or
+    name = "toPath" or
+    name = "toPlainObject" or
+    name = "transform" or
+    name = "unary" or
+    name = "union" or
+    name = "unionBy" or
+    name = "unionWith" or
+    name = "uniq" or
+    name = "uniqBy" or
+    name = "uniqWith" or
+    name = "unset" or
+    name = "unzip" or
+    name = "unzipWith" or
+    name = "update" or
+    name = "updateWith" or
+    name = "values" or
+    name = "valuesIn" or
+    name = "without" or
+    name = "words" or
+    name = "wrap" or
+    name = "xor" or
+    name = "xorBy" or
+    name = "xorWith" or
+    name = "zip" or
+    name = "zipObject" or
+    name = "zipObjectDeep" or
+    name = "zipWith" or
+    name = "entries" or
+    name = "entriesIn" or
+    name = "extend" or
+    name = "extendWith" or
+    name = "add" or
+    name = "attempt" or
+    name = "camelCase" or
+    name = "capitalize" or
+    name = "ceil" or
+    name = "clamp" or
+    name = "clone" or
+    name = "cloneDeep" or
+    name = "cloneDeepWith" or
+    name = "cloneWith" or
+    name = "conformsTo" or
+    name = "deburr" or
+    name = "defaultTo" or
+    name = "divide" or
+    name = "endsWith" or
+    name = "eq" or
+    name = "escape" or
+    name = "escapeRegExp" or
+    name = "every" or
+    name = "find" or
+    name = "findIndex" or
+    name = "findKey" or
+    name = "findLast" or
+    name = "findLastIndex" or
+    name = "findLastKey" or
+    name = "floor" or
+    name = "forEach" or
+    name = "forEachRight" or
+    name = "forIn" or
+    name = "forInRight" or
+    name = "forOwn" or
+    name = "forOwnRight" or
+    name = "get" or
+    name = "gt" or
+    name = "gte" or
+    name = "has" or
+    name = "hasIn" or
+    name = "head" or
+    name = "identity" or
+    name = "includes" or
+    name = "indexOf" or
+    name = "inRange" or
+    name = "invoke" or
+    name = "isArguments" or
+    name = "isArray" or
+    name = "isArrayBuffer" or
+    name = "isArrayLike" or
+    name = "isArrayLikeObject" or
+    name = "isBoolean" or
+    name = "isBuffer" or
+    name = "isDate" or
+    name = "isElement" or
+    name = "isEmpty" or
+    name = "isEqual" or
+    name = "isEqualWith" or
+    name = "isError" or
+    name = "isFinite" or
+    name = "isFunction" or
+    name = "isInteger" or
+    name = "isLength" or
+    name = "isMap" or
+    name = "isMatch" or
+    name = "isMatchWith" or
+    name = "isNaN" or
+    name = "isNative" or
+    name = "isNil" or
+    name = "isNull" or
+    name = "isNumber" or
+    name = "isObject" or
+    name = "isObjectLike" or
+    name = "isPlainObject" or
+    name = "isRegExp" or
+    name = "isSafeInteger" or
+    name = "isSet" or
+    name = "isString" or
+    name = "isSymbol" or
+    name = "isTypedArray" or
+    name = "isUndefined" or
+    name = "isWeakMap" or
+    name = "isWeakSet" or
+    name = "join" or
+    name = "kebabCase" or
+    name = "last" or
+    name = "lastIndexOf" or
+    name = "lowerCase" or
+    name = "lowerFirst" or
+    name = "lt" or
+    name = "lte" or
+    name = "max" or
+    name = "maxBy" or
+    name = "mean" or
+    name = "meanBy" or
+    name = "min" or
+    name = "minBy" or
+    name = "stubArray" or
+    name = "stubFalse" or
+    name = "stubObject" or
+    name = "stubString" or
+    name = "stubTrue" or
+    name = "multiply" or
+    name = "nth" or
+    name = "noConflict" or
+    name = "noop" or
+    name = "now" or
+    name = "pad" or
+    name = "padEnd" or
+    name = "padStart" or
+    name = "parseInt" or
+    name = "random" or
+    name = "reduce" or
+    name = "reduceRight" or
+    name = "repeat" or
+    name = "replace" or
+    name = "result" or
+    name = "round" or
+    name = "runInContext" or
+    name = "sample" or
+    name = "size" or
+    name = "snakeCase" or
+    name = "some" or
+    name = "sortedIndex" or
+    name = "sortedIndexBy" or
+    name = "sortedIndexOf" or
+    name = "sortedLastIndex" or
+    name = "sortedLastIndexBy" or
+    name = "sortedLastIndexOf" or
+    name = "startCase" or
+    name = "startsWith" or
+    name = "subtract" or
+    name = "sum" or
+    name = "sumBy" or
+    name = "template" or
+    name = "times" or
+    name = "toFinite" or
+    name = "toInteger" or
+    name = "toLength" or
+    name = "toLower" or
+    name = "toNumber" or
+    name = "toSafeInteger" or
+    name = "toString" or
+    name = "toUpper" or
+    name = "trim" or
+    name = "trimEnd" or
+    name = "trimStart" or
+    name = "truncate" or
+    name = "unescape" or
+    name = "uniqueId" or
+    name = "upperCase" or
+    name = "upperFirst" or
+    name = "each" or
+    name = "eachRight" or
+    name = "first"
+  }
 }
 
 /**
diff --git a/javascript/ql/test/library-tests/Extend/ExtendCalls.expected b/javascript/ql/test/library-tests/Extend/ExtendCalls.expected
index d930a1880760..89449bc4ff1b 100644
--- a/javascript/ql/test/library-tests/Extend/ExtendCalls.expected
+++ b/javascript/ql/test/library-tests/Extend/ExtendCalls.expected
@@ -23,19 +23,21 @@
 | tst.js:55:1:55:49 | checkDe ... arg())) | OK |
 | tst.js:56:1:56:53 | checkDe ... arg())) | OK |
 | tst.js:57:1:57:56 | checkDe ... arg())) | OK |
-| tst.js:61:1:61:42 | checkSh ... arg())) | OK |
-| tst.js:62:1:62:48 | checkSh ... arg())) | OK |
-| tst.js:63:1:63:54 | checkSh ... arg())) | OK |
-| tst.js:64:1:64:45 | checkSh ... arg())) | OK |
-| tst.js:65:1:65:52 | checkSh ... arg())) | OK |
-| tst.js:66:1:66:53 | checkSh ... arg())) | OK |
-| tst.js:67:1:67:53 | checkSh ... arg())) | OK |
-| tst.js:68:1:68:55 | checkSh ... arg())) | OK |
-| tst.js:69:1:69:52 | checkSh ... arg())) | OK |
-| tst.js:70:1:70:51 | checkSh ... arg())) | OK |
-| tst.js:71:1:71:51 | checkSh ... arg())) | OK |
-| tst.js:72:1:72:53 | checkSh ... arg())) | OK |
-| tst.js:73:1:73:53 | checkSh ... arg())) | OK |
-| tst.js:77:1:77:45 | checkSh ... arg())) | OK |
-| tst.js:78:1:78:55 | checkSh ... arg())) | OK |
-| tst.js:79:1:79:51 | checkSh ... arg())) | OK |
+| tst.js:58:1:58:53 | checkDe ... arg())) | OK |
+| tst.js:59:1:59:56 | checkDe ... arg())) | OK |
+| tst.js:63:1:63:42 | checkSh ... arg())) | OK |
+| tst.js:64:1:64:48 | checkSh ... arg())) | OK |
+| tst.js:65:1:65:54 | checkSh ... arg())) | OK |
+| tst.js:66:1:66:45 | checkSh ... arg())) | OK |
+| tst.js:67:1:67:52 | checkSh ... arg())) | OK |
+| tst.js:68:1:68:53 | checkSh ... arg())) | OK |
+| tst.js:69:1:69:53 | checkSh ... arg())) | OK |
+| tst.js:70:1:70:55 | checkSh ... arg())) | OK |
+| tst.js:71:1:71:52 | checkSh ... arg())) | OK |
+| tst.js:72:1:72:51 | checkSh ... arg())) | OK |
+| tst.js:73:1:73:51 | checkSh ... arg())) | OK |
+| tst.js:74:1:74:53 | checkSh ... arg())) | OK |
+| tst.js:75:1:75:53 | checkSh ... arg())) | OK |
+| tst.js:79:1:79:45 | checkSh ... arg())) | OK |
+| tst.js:80:1:80:55 | checkSh ... arg())) | OK |
+| tst.js:81:1:81:51 | checkSh ... arg())) | OK |
diff --git a/javascript/ql/test/library-tests/Extend/package.json b/javascript/ql/test/library-tests/Extend/package.json
index 92d84b2ed4f5..b140801b8982 100644
--- a/javascript/ql/test/library-tests/Extend/package.json
+++ b/javascript/ql/test/library-tests/Extend/package.json
@@ -14,6 +14,8 @@
 		"js-extend": "^1.0.1",
 		"just-extend": "^1.1.27",
 		"lodash": "^4.17.10",
+		"lodash.defaultsdeep": "^4.6.0",
+		"lodash.mergewith": "^4.6.1",
 		"merge": "^1.2.0",
 		"merge-deep": "^3.0.2",
 		"merge-options": "^1.0.1",
diff --git a/javascript/ql/test/library-tests/Extend/tst.js b/javascript/ql/test/library-tests/Extend/tst.js
index b2cd428183c1..287fe57cdba7 100644
--- a/javascript/ql/test/library-tests/Extend/tst.js
+++ b/javascript/ql/test/library-tests/Extend/tst.js
@@ -55,6 +55,8 @@ checkDeep(require("smart-extend").deep(base(), arg()));
 checkDeep(require("lodash").merge(base(), arg()));
 checkDeep(require("lodash").mergeWith(base(), arg()));
 checkDeep(require("lodash").defaultsDeep(base(), arg()));
+checkDeep(require("lodash.mergewith")(base(), arg()));
+checkDeep(require("lodash.defaultsdeep")(base(), arg()));
 
 // Always shallow