diff --git a/Changes b/Changes
index 6ecc68aba..e2f3dc076 100644
--- a/Changes
+++ b/Changes
@@ -23,6 +23,9 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ****  Fix parameter constant propagation from package, bug1004. [Johan Bjork]
 
+****  Fix array slicing of non-const indexes, bug1006. [Johan Bjork]
+
+
 
 * Verilator 3.878 2015-11-01
 
diff --git a/src/V3Inst.cpp b/src/V3Inst.cpp
index 8a8abffdb..64e226d2c 100644
--- a/src/V3Inst.cpp
+++ b/src/V3Inst.cpp
@@ -36,6 +36,7 @@
 #include "V3Inst.h"
 #include "V3Ast.h"
 #include "V3Changed.h"
+#include "V3Const.h"
 
 //######################################################################
 // Inst state, as a visitor of each AstNode
@@ -250,6 +251,7 @@ private:
 		if (!arrp->subDTypep()->castIfaceRefDType())
 		    return;
 
+		V3Const::constifyParamsEdit(arrselp->rhsp());
 		AstConst *constp = arrselp->rhsp()->castConst();
 		if (!constp) {
 		    nodep->v3error("Unsupported: Non-constant index when passing interface to module");
diff --git a/test_regress/t/t_array_interface.v b/test_regress/t/t_array_interface.v
index 6f688647c..3d8eaa78c 100644
--- a/test_regress/t/t_array_interface.v
+++ b/test_regress/t/t_array_interface.v
@@ -17,6 +17,10 @@ intf.source intf_inst
 assign intf_inst.logic_in_intf = value;
 endmodule
 
+function integer return_3();
+    return 3;
+endfunction
+
 module t
 #(
     parameter N = 6
@@ -27,16 +31,19 @@ module t
 
     generate
         genvar i;
-        for (i = 0;i < 4; i++) begin
+        for (i = 0;i < 3; i++) begin
             assign ifs[i].logic_in_intf  = data[i];
         end
     endgenerate
+    modify_interface m3 (
+        .value(data[return_3()]),
+        .intf_inst(ifs[return_3()]));
 
-    modify_interface m (
+    modify_interface m4 (
     	.value(data[4]),
     	.intf_inst(ifs[4]));
 
-    modify_interface m1 (
+    modify_interface m5 (
     	.value(~ifs[4].logic_in_intf),
     	.intf_inst(ifs[5]));