diff --git a/CHANGELOG-rust.md b/CHANGELOG-rust.md
index 87f27323..93c10783 100644
--- a/CHANGELOG-rust.md
+++ b/CHANGELOG-rust.md
@@ -5,6 +5,8 @@ This changelog tracks the Rust `svdtools` project. See
 
 ## [Unreleased]
 
+* Fast fix for #161
+
 ## [v0.3.2] 2023-10-01
 
 * `_modify` `derivedFrom` for peripherals, clusters, registers and fields
diff --git a/src/patch/mod.rs b/src/patch/mod.rs
index 7d68ad42..738521b9 100644
--- a/src/patch/mod.rs
+++ b/src/patch/mod.rs
@@ -570,6 +570,7 @@ fn make_cpu(cmod: &Hash) -> Result<CpuBuilder> {
 
 /// Find left and right indices of enumeration token in specification string
 fn spec_ind(spec: &str) -> (usize, usize) {
+    let spec = spec.split(',').next().unwrap_or(spec);
     let li = spec
         .bytes()
         .position(|b| b == b'*')
diff --git a/src/patch/peripheral.rs b/src/patch/peripheral.rs
index 85e76cc1..c4d70314 100644
--- a/src/patch/peripheral.rs
+++ b/src/patch/peripheral.rs
@@ -1120,7 +1120,6 @@ fn collect_in_array(
     let mut registers = Vec::new();
     let mut place = usize::MAX;
     let mut i = 0;
-    let (li, ri) = spec_ind(rspec);
     while i < regs.len() {
         match &regs[i] {
             RegisterCluster::Register(Register::Single(r)) if matchname(&r.name, rspec) => {
@@ -1136,6 +1135,7 @@ fn collect_in_array(
         return Err(anyhow!("{path}: registers {rspec} not found"));
     }
     registers.sort_by_key(|r| r.address_offset);
+    let (li, ri) = spec_ind(rspec);
     let dim = registers.len();
     let dim_index = if rmod.contains_key(&"_start_from_zero".to_yaml()) {
         (0..dim).map(|v| v.to_string()).collect::<Vec<_>>()
diff --git a/src/patch/register.rs b/src/patch/register.rs
index 894caad1..fc40abc9 100644
--- a/src/patch/register.rs
+++ b/src/patch/register.rs
@@ -358,7 +358,6 @@ impl RegisterExt for Register {
             let mut fields = Vec::new();
             let mut place = usize::MAX;
             let mut i = 0;
-            let (li, ri) = spec_ind(fspec);
             while i < fs.len() {
                 match &fs[i] {
                     Field::Single(f) if matchname(&f.name, fspec) => {
@@ -374,6 +373,7 @@ impl RegisterExt for Register {
                 return Err(anyhow!("{}: fields {fspec} not found", self.name));
             }
             fields.sort_by_key(|f| f.bit_range.offset);
+            let (li, ri) = spec_ind(fspec);
             let dim = fields.len();
             let dim_index = if fmod.contains_key(&"_start_from_zero".to_yaml()) {
                 (0..dim).map(|v| v.to_string()).collect::<Vec<_>>()
diff --git a/svdtools/patch.py b/svdtools/patch.py
index 00dfeca4..ad2e55bc 100644
--- a/svdtools/patch.py
+++ b/svdtools/patch.py
@@ -194,6 +194,9 @@ def spec_ind(spec):
     """
     Find left and right indices of enumeration token in specification string.
     """
+    comma = spec.find(",")
+    if comma > -1:
+        spec = spec[:comma]
     li1 = spec.find("*")
     li2 = spec.find("?")
     li3 = spec.find("[")