diff --git a/src/leb128.cpp b/src/leb128.cpp
index 0db7bb9bb5..5637bc8a66 100644
--- a/src/leb128.cpp
+++ b/src/leb128.cpp
@@ -67,7 +67,7 @@ std::size_t WriteUleb128(char* addr, unsigned long val) {
  * encodings refer to section "7.6 - Variable Length Data". Return
  * the number of bytes read.
  */
-std::size_t ReadUleb128(char* addr, unsigned long* ret) {
+std::size_t ReadUleb128(const char* addr, unsigned long* ret) {
   unsigned long result = 0;
   int shift = 0;
   std::size_t count = 0;
diff --git a/src/leb128.h b/src/leb128.h
index ca1b28aac5..dc211f1879 100644
--- a/src/leb128.h
+++ b/src/leb128.h
@@ -16,7 +16,7 @@ class raw_istream;
 
 std::size_t SizeUleb128(unsigned long val);
 std::size_t WriteUleb128(char* addr, unsigned long val);
-std::size_t ReadUleb128(char* addr, unsigned long* ret);
+std::size_t ReadUleb128(const char* addr, unsigned long* ret);
 bool ReadUleb128(raw_istream& is, unsigned long* ret);
 
 }  // namespace ntimpl