diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 000000000..071f19cf3
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "plugins/stonesense"]
+	path = plugins/stonesense
+	url = git://github.com/peterix/stonesense.git
diff --git a/plugins/stonesense b/plugins/stonesense
new file mode 160000
index 000000000..7d41a1d6f
--- /dev/null
+++ b/plugins/stonesense
@@ -0,0 +1 @@
+Subproject commit 7d41a1d6f1e770012bfb412aed3ef9b06fd04723
diff --git a/plugins/vdig.cpp b/plugins/vdig.cpp
index 6da466ef9..2453bacad 100644
--- a/plugins/vdig.cpp
+++ b/plugins/vdig.cpp
@@ -293,7 +293,7 @@ DFhackCExport command_result digcircle (Core * c, vector <string> & parameters)
         int top = cy - ((iter + 1) / 2) + adjust;
         int bottom = cy + ((iter + 1) / 2);
         // see where the current 'line' intersects the circle
-        double val = std::sqrt(diameter*diameter - iter*iter);
+        double val = std::sqrt(double(diameter*diameter - iter*iter));
         // adjust for circles with odd diameter
         if(!adjust)
             val -= 1;