diff --git a/src/fst.rs b/src/fst.rs
index aa64813..4285b98 100644
--- a/src/fst.rs
+++ b/src/fst.rs
@@ -75,14 +75,14 @@ impl<R: BufRead + Seek> SignalSource for FstWaveDatabase<R> {
 fn convert_scope_tpe(tpe: FstScopeType) -> ScopeType {
     match tpe {
         FstScopeType::Module => ScopeType::Module,
-        _ => ScopeType::Todo,
+        other => panic!("Unsupported scope type: {:?}", other),
     }
 }
 
 fn convert_var_tpe(tpe: FstVarType) -> VarType {
     match tpe {
         FstVarType::Wire => VarType::Wire,
-        _ => VarType::Todo,
+        other => panic!("Unsupported var type: {:?}", other),
     }
 }
 
diff --git a/src/hierarchy.rs b/src/hierarchy.rs
index 8991683..49d3a25 100644
--- a/src/hierarchy.rs
+++ b/src/hierarchy.rs
@@ -116,7 +116,10 @@ impl HierarchyStringId {
 #[derive(Debug, Clone, Copy)]
 pub enum ScopeType {
     Module,
-    Todo, // placeholder tpe
+    Task,
+    Function,
+    Begin,
+    Fork,
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -126,7 +129,6 @@ pub enum VarType {
     Parameter,
     Integer,
     String,
-    Todo, // placeholder tpe
 }
 
 #[derive(Debug, Clone, Copy)]
diff --git a/src/vcd.rs b/src/vcd.rs
index e5f0d8c..27ecfc7 100644
--- a/src/vcd.rs
+++ b/src/vcd.rs
@@ -158,7 +158,11 @@ fn convert_timescale_unit(name: &[u8]) -> TimescaleUnit {
 fn convert_scope_tpe(tpe: &[u8]) -> ScopeType {
     match tpe {
         b"module" => ScopeType::Module,
-        _ => ScopeType::Todo,
+        b"task" => ScopeType::Task,
+        b"function" => ScopeType::Function,
+        b"begin" => ScopeType::Begin,
+        b"fork" => ScopeType::Fork,
+        _ => panic!("TODO: convert {}", String::from_utf8_lossy(tpe)),
     }
 }
 
diff --git a/tests/diff_tests.rs b/tests/diff_tests.rs
index deb9b7f..5561754 100644
--- a/tests/diff_tests.rs
+++ b/tests/diff_tests.rs
@@ -72,7 +72,10 @@ fn diff_meta(ours: &Hierarchy, ref_header: &vcd::Header) {
 fn waveform_scope_type_to_string(tpe: ScopeType) -> &'static str {
     match tpe {
         ScopeType::Module => "module",
-        ScopeType::Todo => "todo",
+        ScopeType::Task => "task",
+        ScopeType::Function => "function",
+        ScopeType::Begin => "begin",
+        ScopeType::Fork => "fork",
     }
 }
 
@@ -83,7 +86,6 @@ fn waveform_var_type_to_string(tpe: VarType) -> &'static str {
         VarType::Parameter => "parameter",
         VarType::Integer => "integer",
         VarType::String => "string",
-        VarType::Todo => "todo",
     }
 }
 
@@ -247,7 +249,7 @@ fn id_to_int(id: &[u8]) -> Option<u64> {
 
 #[test]
 #[ignore] // TODO: this file has a delta cycle, i.e. the same signal (`/`) changes twice in the same cycle (35185000)
-fn diff_aldec_SPI_Write() {
+fn diff_aldec_spi_write() {
     run_diff_test(
         "inputs/aldec/SPI_Write.vcd",
         "inputs/aldec/SPI_Write.vcd.fst",
@@ -288,10 +290,23 @@ fn diff_gtkwave_perm_current() {
 }
 
 #[test]
-fn diff_icarus_CPU() {
+fn diff_icarus_cpu() {
     run_diff_test("inputs/icarus/CPU.vcd", "inputs/icarus/CPU.vcd.fst");
 }
 
+#[test]
+fn diff_icarus_rv32_soc_tb() {
+    run_diff_test(
+        "inputs/icarus/rv32_soc_TB.vcd",
+        "inputs/icarus/rv32_soc_TB.vcd.fst",
+    );
+}
+
+#[test]
+fn diff_icarus_test1() {
+    run_diff_test("inputs/icarus/test1.vcd", "inputs/icarus/test1.vcd.fst");
+}
+
 #[test]
 fn diff_treadle_gcd() {
     run_diff_test("inputs/treadle/GCD.vcd", "inputs/treadle/GCD.vcd.fst");