diff --git a/tools/preproc/asm_file.cpp b/tools/preproc/asm_file.cpp
index bb296b78b..383010aa3 100644
--- a/tools/preproc/asm_file.cpp
+++ b/tools/preproc/asm_file.cpp
@@ -266,7 +266,7 @@ int AsmFile::ReadString(unsigned char* s)
     {
         m_pos += stringParser.ParseString(m_pos, s, length);
     }
-    catch (std::runtime_error e)
+    catch (std::runtime_error& e)
     {
         RaiseError(e.what());
     }
diff --git a/tools/preproc/c_file.cpp b/tools/preproc/c_file.cpp
index 24b3453e8..2f4bfea7c 100644
--- a/tools/preproc/c_file.cpp
+++ b/tools/preproc/c_file.cpp
@@ -206,7 +206,7 @@ void CFile::TryConvertString()
             {
                 m_pos += stringParser.ParseString(m_pos, s, length);
             }
-            catch (std::runtime_error e)
+            catch (std::runtime_error& e)
             {
                 RaiseError(e.what());
             }