diff --git a/xpcom/build/XPCOMInit.cpp b/xpcom/build/XPCOMInit.cpp
index 766cdb469ad8..d480898e714b 100644
--- a/xpcom/build/XPCOMInit.cpp
+++ b/xpcom/build/XPCOMInit.cpp
@@ -175,6 +175,26 @@ const mozilla::Module kXPCOMModule = {
     nullptr,
     Module::ALLOW_IN_GPU_VR_AND_SOCKET_PROCESS};
 
+// FIXME: Dummy modules to avoid Windows PGO bustage when we have too few
+// modules registered.
+static const mozilla::Module kDummy1 = {mozilla::Module::kVersion};
+static const mozilla::Module kDummy2 = {mozilla::Module::kVersion};
+static const mozilla::Module kDummy3 = {mozilla::Module::kVersion};
+static const mozilla::Module kDummy4 = {mozilla::Module::kVersion};
+static const mozilla::Module kDummy5 = {mozilla::Module::kVersion};
+static const mozilla::Module kDummy6 = {mozilla::Module::kVersion};
+static const mozilla::Module kDummy7 = {mozilla::Module::kVersion};
+static const mozilla::Module kDummy8 = {mozilla::Module::kVersion};
+
+NSMODULE_DEFN(Dummy1) = &kDummy1;
+NSMODULE_DEFN(Dummy2) = &kDummy2;
+NSMODULE_DEFN(Dummy3) = &kDummy3;
+NSMODULE_DEFN(Dummy4) = &kDummy4;
+NSMODULE_DEFN(Dummy5) = &kDummy5;
+NSMODULE_DEFN(Dummy6) = &kDummy6;
+NSMODULE_DEFN(Dummy7) = &kDummy7;
+NSMODULE_DEFN(Dummy8) = &kDummy8;
+
 // gDebug will be freed during shutdown.
 static nsIDebug2* gDebug = nullptr;