diff --git a/src/Base/UnitsSchemaImperial1.cpp b/src/Base/UnitsSchemaImperial1.cpp
index cb226bcb3..57a127cbf 100644
--- a/src/Base/UnitsSchemaImperial1.cpp
+++ b/src/Base/UnitsSchemaImperial1.cpp
@@ -30,6 +30,7 @@
 #include "Exception.h"
 #include "UnitsApi.h"
 #include "UnitsSchemaImperial1.h"
+#include <cmath>
 
 using namespace Base;
 
diff --git a/src/Base/UnitsSchemaInternal.cpp b/src/Base/UnitsSchemaInternal.cpp
index b9c212c49..d4c9e7d3a 100644
--- a/src/Base/UnitsSchemaInternal.cpp
+++ b/src/Base/UnitsSchemaInternal.cpp
@@ -30,6 +30,8 @@
 #include "Exception.h"
 #include "UnitsApi.h"
 #include "UnitsSchemaInternal.h"
+#include <cmath>
+
 
 using namespace Base;
 
diff --git a/src/Base/UnitsSchemaMKS.cpp b/src/Base/UnitsSchemaMKS.cpp
index c9041e7c3..573f58765 100644
--- a/src/Base/UnitsSchemaMKS.cpp
+++ b/src/Base/UnitsSchemaMKS.cpp
@@ -30,6 +30,7 @@
 #include "Exception.h"
 #include "UnitsApi.h"
 #include "UnitsSchemaMKS.h"
+#include <cmath>
 
 using namespace Base;