diff --git a/src/Convert/Inside.hs b/src/Convert/Inside.hs
index 6809f40..06cc1e8 100644
--- a/src/Convert/Inside.hs
+++ b/src/Convert/Inside.hs
@@ -19,6 +19,7 @@ module Convert.Inside (convert) where
 import Convert.Traverse
 import Language.SystemVerilog.AST
 
+import Control.Monad.Writer
 import Data.Maybe (fromMaybe)
 
 convert :: [AST] -> [AST]
@@ -54,12 +55,19 @@ convertStmt (Case u kw expr items) =
         Case u kw expr items
     else if kw /= CaseN then
         error $ "cannot use inside with " ++ show kw
+    else if hasSideEffects expr then
+        Block Seq "" [decl] [stmt]
     else
         foldr ($) defaultStmt $
         map (uncurry $ If NoCheck) $
         zip comps stmts
     where
         exprs = map fst items
+        -- evaluate expressions with side effects once
+        tmp = "sv2v_temp_" ++ shortHash expr
+        decl = Variable Local (TypeOf expr) tmp [] expr
+        stmt = convertStmt (Case u kw (Ident tmp) items)
+        -- underlying inside case elaboration
         itemsNonDefault = filter (not . null . fst) items
         isSpecialInside :: [Expr] -> Bool
         isSpecialInside [Inside Nil _] = True
@@ -71,3 +79,11 @@ convertStmt (Case u kw expr items) =
         stmts = map snd itemsNonDefault
         defaultStmt = fromMaybe Null (lookup [] items)
 convertStmt other = other
+
+hasSideEffects :: Expr -> Bool
+hasSideEffects expr =
+    getAny $ execWriter $ collectNestedExprsM write expr
+    where
+        write :: Expr -> Writer Any ()
+        write Call{} = tell $ Any True
+        write _ = return ()
diff --git a/test/basic/inside_expr.sv b/test/basic/inside_expr.sv
index 74abdac..1d07241 100644
--- a/test/basic/inside_expr.sv
+++ b/test/basic/inside_expr.sv
@@ -1,5 +1,11 @@
 module top;
 
+    function integer sideEffect;
+        input integer inp;
+        $display("sideEffect(%b)", inp);
+        sideEffect = inp;
+    endfunction
+
     initial
         for (logic [1:0] a = 0; a < 3; a++) begin
             if (a inside {2'b01, 2'b00})
@@ -13,6 +19,9 @@ module top;
     initial $display("C", 3'bz11 inside {3'b011});
     initial $display("D", 3'bz11 inside {3'b1?1, 3'b011});
     initial $display("E", 3'bz11 inside {3'b?01, 3'b011});
+    // TODO: Add support for inside expressions with side effects.
+    // initial $display("F", sideEffect(3'bz11) inside {3'b?11});
+    // initial $display("G", 3'bz11 inside {sideEffect(3'b?11)});
 
     generate
         begin : patterns
@@ -53,7 +62,7 @@ module top;
 
     function integer test3;
         input integer inp;
-        case (inp) inside
+        case (1 + sideEffect(inp)) inside
             [16:23]: return 1;
             [32:47]: return 2;
             default: return 0;
diff --git a/test/basic/inside_expr.v b/test/basic/inside_expr.v
index 39fbc51..65ed4a7 100644
--- a/test/basic/inside_expr.v
+++ b/test/basic/inside_expr.v
@@ -1,5 +1,13 @@
 module top;
 
+    function integer sideEffect;
+        input integer inp;
+        begin
+            $display("sideEffect(%b)", inp);
+            sideEffect = inp;
+        end
+    endfunction
+
     initial begin : foo
         reg [1:0] a;
         for (a = 0; a < 3; a++) begin
@@ -15,6 +23,14 @@ module top;
     initial $display("C", 1'bx);
     initial $display("D", 1'bx);
     initial $display("E", 1'bx);
+    // TODO: Add support for inside expressions with side effects.
+    // initial begin : bar
+    //     integer tmp;
+    //     tmp = sideEffect(3'bz11);
+    //     $display("F", 1'b1);
+    //     tmp = sideEffect(3'b?11);
+    //     $display("G", 1'b1);
+    // end
 
     function test1;
         input [2:0] inp;
@@ -54,6 +70,7 @@ module top;
     function [0:31] test3;
         input integer inp;
         begin
+            inp = 1 + sideEffect(inp);
             if (16 <= inp && inp <= 23) test3 = 1;
             else if (32 <= inp && inp <= 47) test3 = 2;
             else if (inp == 0 || (60 <= inp && inp <= 61) || inp == 4) test3 = 3;