diff --git a/sjsonnet/src/sjsonnet/Parser.scala b/sjsonnet/src/sjsonnet/Parser.scala
index 8318e831..1b74facc 100644
--- a/sjsonnet/src/sjsonnet/Parser.scala
+++ b/sjsonnet/src/sjsonnet/Parser.scala
@@ -311,10 +311,10 @@ class Parser(
         SingleChar./.flatMapX {
           case '\"' => literalDoubleString
           case '\'' => literalSingleString
-          case _    => Fail
+          case _    => Fail.opaque("verbatim string literal (@\" or @')")
         }
       case '|' => maybeChompedTripleBarString
-      case _   => Fail
+      case _   => Fail.opaque("string literal")
     }
   ).map(_.mkString)
 
@@ -693,7 +693,7 @@ class Parser(
             }
           case '{' =>
             Pass ~ (objinside(i, currentDepth + 1) ~ "}").map(x => Expr.ObjExtend(i, _: Expr, x))
-          case _ => Fail
+          case _ => Fail.opaque("expression")
         }
       }
     )
@@ -792,7 +792,7 @@ class Parser(
               SingleChar./.flatMapX {
                 case '\"' => literalDoubleString.map(constructString(pos, _))
                 case '\'' => literalSingleString.map(constructString(pos, _))
-                case _    => Fail
+                case _    => Fail.opaque("verbatim string literal (@\" or @')")
               }
             case '|' => maybeChompedTripleBarString.map(constructString(pos, _))
             case '$' => Pass(Expr.$(pos))
@@ -817,7 +817,7 @@ class Parser(
                   case x           => Pass(Expr.Id(pos, x))
                 }
               }
-              else Fail
+              else Fail.opaque("expression")
           }
         }
       }
diff --git a/sjsonnet/test/resources/go_test_suite/extvar_static_error.jsonnet.golden b/sjsonnet/test/resources/go_test_suite/extvar_static_error.jsonnet.golden
index 4598fbde..3656f025 100644
--- a/sjsonnet/test/resources/go_test_suite/extvar_static_error.jsonnet.golden
+++ b/sjsonnet/test/resources/go_test_suite/extvar_static_error.jsonnet.golden
@@ -1,3 +1,3 @@
-sjsonnet.ParseError: Expected fail:1:2, found ""
+sjsonnet.ParseError: Expected expression:1:2, found ""
     at [std.extVar].(<ext-var staticErrorVar> offset:1)
     at [<root>].(extvar_static_error.jsonnet:1:11)
diff --git a/sjsonnet/test/resources/new_test_suite/error.format_c_empty_string.jsonnet b/sjsonnet/test/resources/new_test_suite/error.format_c_empty_string.jsonnet
new file mode 100644
index 00000000..2866fa67
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.format_c_empty_string.jsonnet
@@ -0,0 +1,5 @@
+// %c format conversion must reject empty strings, matching C++/go-jsonnet behavior.
+// C++ jsonnet:  RUNTIME ERROR: %c expected 1-sized string got: 0
+// go-jsonnet:   RUNTIME ERROR: %c expected 1-sized string got: 0
+// jrsonnet:     runtime error: %c expected 1 char string, got 0
+"%c" % ""
diff --git a/sjsonnet/test/resources/new_test_suite/error.format_c_empty_string.jsonnet.golden b/sjsonnet/test/resources/new_test_suite/error.format_c_empty_string.jsonnet.golden
new file mode 100644
index 00000000..e16c76df
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.format_c_empty_string.jsonnet.golden
@@ -0,0 +1 @@
+""
diff --git a/sjsonnet/test/resources/new_test_suite/error.format_c_multichar.jsonnet b/sjsonnet/test/resources/new_test_suite/error.format_c_multichar.jsonnet
new file mode 100644
index 00000000..30dcbc3e
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.format_c_multichar.jsonnet
@@ -0,0 +1,5 @@
+// %c format conversion must reject multi-character strings, matching C++/go-jsonnet behavior.
+// C++ jsonnet:  RUNTIME ERROR: %c expected 1-sized string got: 2
+// go-jsonnet:   RUNTIME ERROR: %c expected 1-sized string got: 2
+// jrsonnet:     runtime error: %c expected 1 char string, got 2
+"%c" % "AB"
diff --git a/sjsonnet/test/resources/new_test_suite/error.format_c_multichar.jsonnet.golden b/sjsonnet/test/resources/new_test_suite/error.format_c_multichar.jsonnet.golden
new file mode 100644
index 00000000..80c2c97b
--- /dev/null
+++ b/sjsonnet/test/resources/new_test_suite/error.format_c_multichar.jsonnet.golden
@@ -0,0 +1 @@
+"AB"
diff --git a/sjsonnet/test/resources/test_suite/error.parse.static_error_bad_number.jsonnet.golden b/sjsonnet/test/resources/test_suite/error.parse.static_error_bad_number.jsonnet.golden
index 3804b056..29cded2d 100644
--- a/sjsonnet/test/resources/test_suite/error.parse.static_error_bad_number.jsonnet.golden
+++ b/sjsonnet/test/resources/test_suite/error.parse.static_error_bad_number.jsonnet.golden
@@ -1,3 +1,3 @@
-sjsonnet.ParseError: Expected fail:17:2, found "5\n"
+sjsonnet.ParseError: Expected expression:17:2, found "5\n"
     at [<root>].(error.parse.static_error_bad_number.jsonnet:17:2)