diff --git a/src/xSTIR/cSTIR/cstir.cpp b/src/xSTIR/cSTIR/cstir.cpp
index cc5076d1d..cae22fa01 100644
--- a/src/xSTIR/cSTIR/cstir.cpp
+++ b/src/xSTIR/cSTIR/cstir.cpp
@@ -1168,8 +1168,8 @@ cSTIR_objectiveFunctionValue(void* ptr_f, void* ptr_i)
 		ObjectiveFunction3DF& fun = objectFromHandle< ObjectiveFunction3DF>(ptr_f);
 		STIRImageData& id = objectFromHandle<STIRImageData>(ptr_i);
 		Image3DF& image = id.data();
-		float v = (float)fun.compute_objective_function(image);
-		return dataHandle<float>(v);
+		double v = fun.compute_objective_function(image);
+		return dataHandle<double>(v);
 	}
 	CATCH;
 }
diff --git a/src/xSTIR/pSTIR/STIR.py b/src/xSTIR/pSTIR/STIR.py
index e614aa785..89e8ef8c5 100644
--- a/src/xSTIR/pSTIR/STIR.py
+++ b/src/xSTIR/pSTIR/STIR.py
@@ -2714,7 +2714,7 @@ def value(self, image):
         assert_validity(image, ImageData)
         handle = pystir.cSTIR_objectiveFunctionValue(self.handle, image.handle)
         check_status(handle)
-        v = pyiutil.floatDataFromHandle(handle)
+        v = pyiutil.doubleDataFromHandle(handle)
         pyiutil.deleteDataHandle(handle)
         return v