diff --git a/include/boost/math/distributions/cauchy.hpp b/include/boost/math/distributions/cauchy.hpp
index c0c76addf..00a9ac9ac 100644
--- a/include/boost/math/distributions/cauchy.hpp
+++ b/include/boost/math/distributions/cauchy.hpp
@@ -18,6 +18,7 @@
 #include <boost/math/tools/tuple.hpp>
 #include <boost/math/tools/numeric_limits.hpp>
 #include <boost/math/tools/precision.hpp>
+#include <boost/math/tools/promotion.hpp>
 #include <boost/math/constants/constants.hpp>
 #include <boost/math/distributions/complement.hpp>
 #include <boost/math/distributions/detail/common_error_handling.hpp>
diff --git a/include/boost/math/distributions/normal.hpp b/include/boost/math/distributions/normal.hpp
index 9d973fb53..aa27c8feb 100644
--- a/include/boost/math/distributions/normal.hpp
+++ b/include/boost/math/distributions/normal.hpp
@@ -18,6 +18,7 @@
 #include <boost/math/tools/config.hpp>
 #include <boost/math/tools/tuple.hpp>
 #include <boost/math/tools/numeric_limits.hpp>
+#include <boost/math/tools/promotion.hpp>
 #include <boost/math/distributions/fwd.hpp>
 #include <boost/math/special_functions/erf.hpp> // for erf/erfc.
 #include <boost/math/distributions/complement.hpp>
diff --git a/include/boost/math/distributions/triangular.hpp b/include/boost/math/distributions/triangular.hpp
index b333ddbc3..e14d3f84a 100644
--- a/include/boost/math/distributions/triangular.hpp
+++ b/include/boost/math/distributions/triangular.hpp
@@ -18,6 +18,7 @@
 
 #include <boost/math/tools/config.hpp>
 #include <boost/math/tools/tuple.hpp>
+#include <boost/math/tools/promotion.hpp>
 #include <boost/math/distributions/fwd.hpp>
 #include <boost/math/special_functions/expm1.hpp>
 #include <boost/math/distributions/detail/common_error_handling.hpp>
diff --git a/include/boost/math/distributions/uniform.hpp b/include/boost/math/distributions/uniform.hpp
index 328fc6133..08472f95e 100644
--- a/include/boost/math/distributions/uniform.hpp
+++ b/include/boost/math/distributions/uniform.hpp
@@ -18,6 +18,7 @@
 
 #include <boost/math/tools/config.hpp>
 #include <boost/math/tools/tuple.hpp>
+#include <boost/math/tools/promotion.hpp>
 #include <boost/math/distributions/fwd.hpp>
 #include <boost/math/distributions/detail/common_error_handling.hpp>
 #include <boost/math/distributions/complement.hpp>