diff --git a/platform/javascript/detect.py b/platform/javascript/detect.py
index ca400632c8..4564bacaa3 100644
--- a/platform/javascript/detect.py
+++ b/platform/javascript/detect.py
@@ -119,6 +119,10 @@ def configure(env):
 
     ## Link flags
 
+    # We use IDBFS in javascript_main.cpp. Since Emscripten 1.39.1 it needs to
+    # be linked explicitly.
+    env.Append(LIBS=['idbfs.js'])
+
     env.Append(LINKFLAGS=['-s', 'BINARYEN=1'])
     env.Append(LINKFLAGS=['-s', 'BINARYEN_TRAP_MODE=\'clamp\''])