2 files changed, 8 insertions, 0 deletions
diff --git a/src/postamble.js b/src/postamble.js
index cf863669..24b8e4a1 100644
--- a/src/postamble.js
+++ b/src/postamble.js
@@ -38,6 +38,11 @@ function run(args) {
 
   if (Module['preRun']) {
     Module['preRun']();
+    if (runDependencies > 0) {
+      // preRun added a dependency, run will be called later
+      Module['preRun'] = null;
+      return 0;
+    }
   }
 
   var ret = null;
diff --git a/src/preamble.js b/src/preamble.js
index e9ba2009..997e5ab3 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -854,6 +854,9 @@ var STRING_TABLE = [];
 // do asynchronous work before running, increment this and
 // decrement it. Incrementing must happen in a place like
 // PRE_RUN_ADDITIONS (used by emcc to add file preloading).
+// Note that you can add dependencies in preRun, even though
+// it happens right before run - run will be postponed until
+// the dependencies are met.
 var runDependencies = 0;
 function addRunDependency() {
   runDependencies++;