diff --git a/src/processor/source_line_resolver.cc b/src/processor/source_line_resolver.cc
index a81d4690..6d5f219c 100644
--- a/src/processor/source_line_resolver.cc
+++ b/src/processor/source_line_resolver.cc
@@ -165,6 +165,10 @@ bool SourceLineResolver::LoadModule(const string &module_name,
   return true;
 }
 
+bool SourceLineResolver::HasModule(const string &module_name) const {
+  return modules_->find(module_name) != modules_->end();
+}
+
 void SourceLineResolver::FillSourceLineInfo(StackFrame *frame,
                                             StackFrameInfo *frame_info) const {
   ModuleMap::const_iterator it = modules_->find(frame->module_name);
diff --git a/src/processor/source_line_resolver.h b/src/processor/source_line_resolver.h
index 6948a86a..1490f715 100644
--- a/src/processor/source_line_resolver.h
+++ b/src/processor/source_line_resolver.h
@@ -60,6 +60,9 @@ class SourceLineResolver {
   // map_file should contain line/address mappings for this module.
   bool LoadModule(const string &module_name, const string &map_file);
 
+  // Returns true if a module with the given name has been loaded.
+  bool HasModule(const string &module_name) const;
+
   // Fills in the function_base, function_name, source_file_name,
   // and source_line fields of the StackFrame.  The instruction and
   // module_name fields must already be filled in.  Additional debugging
diff --git a/src/processor/source_line_resolver_unittest.cc b/src/processor/source_line_resolver_unittest.cc
index 053bc21e..0b70b43f 100644
--- a/src/processor/source_line_resolver_unittest.cc
+++ b/src/processor/source_line_resolver_unittest.cc
@@ -69,7 +69,9 @@ static bool RunTests() {
 
   SourceLineResolver resolver;
   ASSERT_TRUE(resolver.LoadModule("module1", testdata_dir + "/module1.out"));
+  ASSERT_TRUE(resolver.HasModule("module1"));
   ASSERT_TRUE(resolver.LoadModule("module2", testdata_dir + "/module2.out"));
+  ASSERT_TRUE(resolver.HasModule("module2"));
 
   StackFrame frame;
   StackFrameInfo frame_info;
@@ -112,8 +114,11 @@ static bool RunTests() {
 
   ASSERT_FALSE(resolver.LoadModule("module3",
                                    testdata_dir + "/module3_bad.out"));
+  ASSERT_FALSE(resolver.HasModule("module3"));
   ASSERT_FALSE(resolver.LoadModule("module4",
                                    testdata_dir + "/invalid-filename"));
+  ASSERT_FALSE(resolver.HasModule("module4"));
+  ASSERT_FALSE(resolver.HasModule("invalid-module"));
   return true;
 }
 
diff --git a/src/processor/stackwalker.cc b/src/processor/stackwalker.cc
index 2f74e924..e5c79cc2 100644
--- a/src/processor/stackwalker.cc
+++ b/src/processor/stackwalker.cc
@@ -78,14 +78,13 @@ void Stackwalker::Walk(StackFrames *frames) {
       if (module) {
         frame->module_name = *(module->GetName());
         frame->module_base = module->base_address();
-        if (modules_ && supplier_) {
-          string symbol_file =
-            supplier_->GetSymbolFile(module);
+        if (!resolver.HasModule(frame->module_name) && supplier_) {
+          string symbol_file = supplier_->GetSymbolFile(module);
           if (!symbol_file.empty()) {
-            resolver.LoadModule(*(module->GetName()), symbol_file);
-            resolver.FillSourceLineInfo(frame.get(), frame_info.get());
+            resolver.LoadModule(frame->module_name, symbol_file);
           }
         }
+        resolver.FillSourceLineInfo(frame.get(), frame_info.get());
       }
     }