diff --git a/compiler/rustc_driver_impl/src/highlighter.rs b/compiler/rustc_driver_impl/src/highlighter.rs
index 70b73cc29b723..16b8f58bca1e6 100644
--- a/compiler/rustc_driver_impl/src/highlighter.rs
+++ b/compiler/rustc_driver_impl/src/highlighter.rs
@@ -106,7 +106,7 @@ impl Highlighter {
                     // This heuristic test is to detect if the identifier is
                     // a function call. If it is, then the function identifier is
                     // colored differently.
-                    if code[*len_accum..*len_accum + len + 1].ends_with('(') {
+                    if code[*len_accum + len..].starts_with('(') {
                         style = style.fg_color(Some(Color::Ansi(FUNCTION_COLOR)));
                     }
                     // The `derive` keyword is colored differently.
diff --git a/tests/ui/explain/explanation-code-rendering-edge-case-regression.rs b/tests/ui/explain/explanation-code-rendering-edge-case-regression.rs
new file mode 100644
index 0000000000000..0d12c71bb8736
--- /dev/null
+++ b/tests/ui/explain/explanation-code-rendering-edge-case-regression.rs
@@ -0,0 +1,3 @@
+//@ compile-flags: --explain E0602 --color always --error-format=human
+//@ check-pass
+// Ensure that we trigger the condition for #156326 without ICEing.
diff --git a/tests/ui/explain/explanation-code-rendering-edge-case-regression.stdout b/tests/ui/explain/explanation-code-rendering-edge-case-regression.stdout
new file mode 100644
index 0000000000000..962d129214349
--- /dev/null
+++ b/tests/ui/explain/explanation-code-rendering-edge-case-regression.stdout
@@ -0,0 +1,7 @@
+An unknown or invalid lint was used on the command line.
+
+Erroneous code example:
+
+rustc -D bogus rust_file.rs
+
+Maybe you just misspelled the lint name or the lint doesn't exist anymore. Either way, try to update/remove it in order to fix the error.