diff --git a/src/xspice/icm/table/support/interp.h b/src/xspice/icm/table/support/interp.h
new file mode 100644
index 000000000..dbbd2be42
--- /dev/null
+++ b/src/xspice/icm/table/support/interp.h
@@ -0,0 +1,8 @@
+#ifndef interp_h_included
+#define interp_h_included
+double BilinearInterpolation(double x, double y,
+        int xind, int yind, double **td);
+double TrilinearInterpolation(double x, double y, double z,
+        int xind, int yind, int zind, double ***td);
+int findCrossOver(double arr[], int n, double x);
+#endif /* include guard */