diff --git a/src/shared/proparser/qmakebuiltins.cpp b/src/shared/proparser/qmakebuiltins.cpp
index c4b81f6f932..bf6023b9ff9 100644
--- a/src/shared/proparser/qmakebuiltins.cpp
+++ b/src/shared/proparser/qmakebuiltins.cpp
@@ -76,7 +76,7 @@ enum ExpandFunc {
     E_SPRINTF, E_FORMAT_NUMBER, E_JOIN, E_SPLIT, E_BASENAME, E_DIRNAME, E_SECTION,
     E_FIND, E_SYSTEM, E_UNIQUE, E_REVERSE, E_QUOTE, E_ESCAPE_EXPAND,
     E_UPPER, E_LOWER, E_FILES, E_PROMPT, E_RE_ESCAPE, E_VAL_ESCAPE,
-    E_REPLACE, E_SORT_DEPENDS, E_RESOLVE_DEPENDS
+    E_REPLACE, E_SORT_DEPENDS, E_RESOLVE_DEPENDS, E_ENUMERATE_VARS
 };
 
 enum TestFunc {
@@ -121,7 +121,8 @@ void QMakeEvaluator::initFunctionStatics()
         { "prompt", E_PROMPT },
         { "replace", E_REPLACE },
         { "sort_depends", E_SORT_DEPENDS },
-        { "resolve_depends", E_RESOLVE_DEPENDS }
+        { "resolve_depends", E_RESOLVE_DEPENDS },
+        { "enumerate_vars", E_ENUMERATE_VARS },
     };
     for (unsigned i = 0; i < sizeof(expandInits)/sizeof(expandInits[0]); ++i)
         statics.expands.insert(ProString(expandInits[i].name), expandInits[i].func);
@@ -809,6 +810,15 @@ ProStringList QMakeEvaluator::evaluateExpandFunction(
             }
         }
         break;
+    case E_ENUMERATE_VARS: {
+        QSet<ProString> keys;
+        foreach (const ProValueMap &vmap, m_valuemapStack)
+            for (ProValueMap::ConstIterator it = vmap.constBegin(); it != vmap.constEnd(); ++it)
+                keys.insert(it.key());
+        ret.reserve(keys.size());
+        foreach (const ProString &key, keys)
+            ret << key;
+        break; }
     case E_INVALID:
         evalError(fL1S("'%1' is not a recognized replace function.")
                   .arg(func.toQString(m_tmp1)));