diff --git a/src/V3LinkParse.cpp b/src/V3LinkParse.cpp
index 5bf8633a7..75c1e9445 100644
--- a/src/V3LinkParse.cpp
+++ b/src/V3LinkParse.cpp
@@ -1151,6 +1151,10 @@ class LinkParseVisitor final : public VNVisitor {
     }
 
     void visit(AstCovergroup* nodep) override {
+        // If we're already inside a covergroup class, this is the sentinel AstCovergroup
+        // node carrying the clocking event for V3Covergroup — don't re-transform it.
+        if (m_modp && VN_IS(m_modp, Class) && VN_CAST(m_modp, Class)->isCovergroup()) return;
+
         // Transform raw parse-time AstCovergroup into a fully-formed AstClass
         cleanFileline(nodep);
 
diff --git a/src/verilog.y b/src/verilog.y
index 9af8218ad..c7b436625 100644
--- a/src/verilog.y
+++ b/src/verilog.y
@@ -6913,7 +6913,7 @@ covergroup_declaration<nodep>:  // ==IEEE: covergroup_declaration
                               else
                                   sampleArgsp = $4;
                           }
-                          $$ = new AstCovergroup{$<fl>2, *$2, static_cast<AstVar*>($3),
+                          $$ = new AstCovergroup{$<fl>1, *$2, static_cast<AstVar*>($3),
                                                  static_cast<AstVar*>(sampleArgsp), $6, clockp};
                           GRAMMARP->endLabel($<fl>8, $$, $8); }
         |        yCOVERGROUP yEXTENDS idAny ';'