diff --git a/lib/Checker/StreamChecker.cpp b/lib/Checker/StreamChecker.cpp
new file mode 100644
index 0000000..80c29a1
--- /dev/null
+++ b/lib/Checker/StreamChecker.cpp
@@ -0,0 +1,116 @@
+//===-- StreamChecker.cpp -----------------------------------------*- C++ -*--//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines checkers that model and check stream handling functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "GRExprEngineExperimentalChecks.h"
+#include "clang/Checker/BugReporter/BugType.h"
+#include "clang/Checker/PathSensitive/CheckerVisitor.h"
+#include "clang/Checker/PathSensitive/GRState.h"
+#include "clang/Checker/PathSensitive/GRStateTrait.h"
+#include "clang/Checker/PathSensitive/SymbolManager.h"
+#include "llvm/ADT/ImmutableMap.h"
+
+using namespace clang;
+
+namespace {
+
+class StreamChecker : public CheckerVisitor<StreamChecker> {
+  IdentifierInfo *II_fopen, *II_fread;
+  BuiltinBug *BT_nullfp;
+
+public:
+  StreamChecker() : II_fopen(0), II_fread(0), BT_nullfp(0) {}
+
+  static void *getTag() {
+    static int x;
+    return &x;
+  }
+
+  virtual bool EvalCallExpr(CheckerContext &C, const CallExpr *CE);
+
+private:
+  void FOpen(CheckerContext &C, const CallExpr *CE);
+  void FRead(CheckerContext &C, const CallExpr *CE);
+};
+
+}
+
+void clang::RegisterStreamChecker(GRExprEngine &Eng) {
+  Eng.registerCheck(new StreamChecker());
+}
+
+bool StreamChecker::EvalCallExpr(CheckerContext &C, const CallExpr *CE) {
+  const GRState *state = C.getState();
+  const Expr *Callee = CE->getCallee();
+  SVal L = state->getSVal(Callee);
+  const FunctionDecl *FD = L.getAsFunctionDecl();
+  if (!FD)
+    return false;
+
+  ASTContext &Ctx = C.getASTContext();
+  if (!II_fopen)
+    II_fopen = &Ctx.Idents.get("fopen");
+
+  if (!II_fread)
+    II_fread = &Ctx.Idents.get("fread");
+
+  if (FD->getIdentifier() == II_fopen) {
+    FOpen(C, CE);
+    return true;
+  }
+
+  if (FD->getIdentifier() == II_fread) {
+    FRead(C, CE);
+    return true;
+  }
+
+  return false;
+}
+
+void StreamChecker::FOpen(CheckerContext &C, const CallExpr *CE) {
+  const GRState *state = C.getState();
+  unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
+  ValueManager &ValMgr = C.getValueManager();
+  SVal RetVal = ValMgr.getConjuredSymbolVal(0, CE, Count);
+  state = state->BindExpr(CE, RetVal);
+
+  ConstraintManager &CM = C.getConstraintManager();
+  // Bifurcate the state into two: one with a valid FILE* pointer, the other
+  // with a NULL.
+  const GRState *stateNotNull, *stateNull;
+  llvm::tie(stateNotNull, stateNull) 
+    = CM.AssumeDual(state, cast<DefinedSVal>(RetVal));
+
+  C.addTransition(stateNotNull);
+  C.addTransition(stateNull);
+}
+
+void StreamChecker::FRead(CheckerContext &C, const CallExpr *CE) {
+  const GRState *state = C.getState();
+
+  // Assume CallAndMessageChecker has been run.
+  const DefinedSVal &StreamVal=cast<DefinedSVal>(state->getSVal(CE->getArg(3)));
+
+  ConstraintManager &CM = C.getConstraintManager();
+  const GRState *stateNotNull, *stateNull;
+  llvm::tie(stateNotNull, stateNull) = CM.AssumeDual(state, StreamVal);
+
+  if (!stateNotNull && stateNull) {
+    if (ExplodedNode *N = C.GenerateSink(stateNull)) {
+      if (!BT_nullfp)
+        BT_nullfp = new BuiltinBug("NULL stream pointer",
+                                   "Stream pointer might be NULL.");
+      BugReport *R = new BugReport(*BT_nullfp, BT_nullfp->getDescription(), N);
+      C.EmitReport(R);
+    }
+  }
+}