diff --git a/include/boost/assert/source_location.hpp b/include/boost/assert/source_location.hpp
index c6eae32..3c2d60e 100644
--- a/include/boost/assert/source_location.hpp
+++ b/include/boost/assert/source_location.hpp
@@ -9,11 +9,14 @@
 
 #include <boost/config.hpp>
 #include <boost/cstdint.hpp>
-#include <iosfwd>
 #include <string>
 #include <cstdio>
 #include <cstring>
 
+#if !defined(BOOST_NO_IOSTREAM)
+#include <iosfwd>
+#endif
+
 #if defined(__cpp_lib_source_location) && __cpp_lib_source_location >= 201907L
 # include <source_location>
 #endif
@@ -132,12 +135,16 @@ public:
     }
 };
 
+#if !defined(BOOST_NO_IOSTREAM)
+
 template<class E, class T> std::basic_ostream<E, T> & operator<<( std::basic_ostream<E, T> & os, source_location const & loc )
 {
     os << loc.to_string();
     return os;
 }
 
+#endif
+
 } // namespace boost
 
 #if defined(BOOST_DISABLE_CURRENT_LOCATION)