diff --git a/src/rose/rose_build_bytecode.cpp b/src/rose/rose_build_bytecode.cpp
index c89d2073..0dbe20ea 100644
--- a/src/rose/rose_build_bytecode.cpp
+++ b/src/rose/rose_build_bytecode.cpp
@@ -4649,6 +4649,7 @@ rose_literal_id getFragment(const rose_literal_id &lit) {
     return frag;
 }
 
+static
 map<u32, LitFragment> groupByFragment(const RoseBuildImpl &build) {
     u32 frag_id = 0;
     map<u32, LitFragment> final_to_frag;
diff --git a/src/rose/rose_build_impl.h b/src/rose/rose_build_impl.h
index e9ba5f55..dc696ddd 100644
--- a/src/rose/rose_build_impl.h
+++ b/src/rose/rose_build_impl.h
@@ -651,8 +651,6 @@ void normaliseLiteralMask(const ue2_literal &s, std::vector<u8> &msk,
 bool canImplementGraphs(const RoseBuildImpl &tbi);
 #endif
 
-std::map<u32, LitFragment> groupByFragment(const RoseBuildImpl &build);
-
 } // namespace ue2
 
 #endif /* ROSE_BUILD_IMPL_H_17E20A3C6935D6 */