diff --git a/include/sta/Search.hh b/include/sta/Search.hh
index 2c1f2504..5b3d6772 100644
--- a/include/sta/Search.hh
+++ b/include/sta/Search.hh
@@ -238,25 +238,26 @@ public:
 		     const RiseFall *to_rf,
 		     const MinMax *min_max,
 		     const PathAnalysisPt *path_ap);
-  virtual Tag *thruTag(Tag *from_tag,
-		       Edge *edge,
-		       const RiseFall *to_rf,
-		       const MinMax *min_max,
- 		       const PathAnalysisPt *path_ap);
-  virtual Tag *thruClkTag(PathVertex *from_path,
-			  Tag *from_tag,
-			  bool to_propagates_clk,
-			  Edge *edge,
-			  const RiseFall *to_rf,
-			  const MinMax *min_max,
-			  const PathAnalysisPt *path_ap);
+  Tag *thruTag(Tag *from_tag,
+               Edge *edge,
+               const RiseFall *to_rf,
+               const MinMax *min_max,
+               const PathAnalysisPt *path_ap);
+  Tag *thruClkTag(PathVertex *from_path,
+                  Tag *from_tag,
+                  bool to_propagates_clk,
+                  Edge *edge,
+                  const RiseFall *to_rf,
+                  const MinMax *min_max,
+                  const PathAnalysisPt *path_ap);
   ClkInfo *thruClkInfo(PathVertex *from_path,
-		       ClkInfo *from_tag_clk,
-		       Edge *edge,
-		       Vertex *to_vertex,
-		       const Pin *to_pin,
-		       const MinMax *min_max,
- 		       const PathAnalysisPt *path_ap);
+                       ClkInfo *from_clk_info,
+                       bool from_is_clk,
+                       Edge *edge,
+                       const Pin *to_pin,
+                       bool to_is_clk,
+                       const MinMax *min_max,
+                       const PathAnalysisPt *path_ap);
   ClkInfo *clkInfoWithCrprClkPath(ClkInfo *from_clk_info,
 				  PathVertex *from_path,
 				  const PathAnalysisPt *path_ap);
diff --git a/search/ClkInfo.hh b/search/ClkInfo.hh
index 2e4c198e..3989f368 100644
--- a/search/ClkInfo.hh
+++ b/search/ClkInfo.hh
@@ -54,8 +54,8 @@ public:
   const Arrival &insertion() const { return insertion_; }
   ClockUncertainties *uncertainties() const { return uncertainties_; }
   PathAPIndex pathAPIndex() const { return path_ap_index_; }
-  // Clock path for the last driver in the clock network used for
-  // crpr resolution.
+  // Clock path used for crpr resolution.
+  // Null for clocks because the path cannot point to itself.
   PathVertexRep &crprClkPath() { return crpr_clk_path_; }
   const PathVertexRep &crprClkPath() const { return crpr_clk_path_; }
   VertexId crprClkVertexId() const;
diff --git a/search/Crpr.cc b/search/Crpr.cc
index af1b14e8..92bae4b9 100644
--- a/search/Crpr.cc
+++ b/search/Crpr.cc
@@ -46,20 +46,20 @@ CheckCrpr::CheckCrpr(StaState *sta) :
 {
 }
 
-PathVertex *
+void
 CheckCrpr::clkPathPrev(const PathVertex *path,
-		       PathVertex &tmp)
+		       PathVertex &prev)
 
 {
   Vertex *vertex = path->vertex(this);
   int arrival_index;
   bool exists;
   path->arrivalIndex(arrival_index, exists);
-  tmp = clkPathPrev(vertex, arrival_index);
-  if (tmp.isNull())
-    return nullptr;
+  PathVertexRep *prevs = graph_->prevPaths(vertex);
+  if (prevs)
+    prev.init(prevs[arrival_index], this);
   else
-    return &tmp;
+    criticalError(2200, "missing prev paths");
 }
 
 PathVertex
@@ -70,7 +70,7 @@ CheckCrpr::clkPathPrev(Vertex *vertex,
   if (prevs)
     return PathVertex(prevs[arrival_index], this);
   else {
-    criticalError(248, "missing prev paths");
+    criticalError(2201, "missing prev paths");
     return PathVertex();
   }
 }
@@ -152,13 +152,22 @@ CheckCrpr::checkCrpr1(const Path *src_path,
 {
   crpr = 0.0;
   crpr_pin = nullptr;
-  ClkInfo *src_clk_info = src_path->tag(this)->clkInfo();
+  const Tag *src_tag = src_path->tag(this);
+  ClkInfo *src_clk_info = src_tag->clkInfo();
   ClkInfo *tgt_clk_info = tgt_clk_path->tag(this)->clkInfo();
   const Clock *src_clk = src_clk_info->clock();
   const Clock *tgt_clk = tgt_clk_info->clock();
-  const PathVertex src_clk_path1(src_clk_info->crprClkPath(), this);
-  const PathVertex *src_clk_path =
-    src_clk_path1.isNull() ? nullptr : &src_clk_path1;
+  PathVertex src_clk_path1;
+  PathVertexRep &src_crpr_clk_path = src_clk_info->crprClkPath();
+  const PathVertex *src_clk_path = nullptr;
+  if (src_tag->isClock()) {
+    src_clk_path1.init(src_path->vertex(this), src_path->tag(this), this);
+    src_clk_path = &src_clk_path1;
+  }
+  else if (!src_crpr_clk_path.isNull()) {
+    src_clk_path1.init(src_crpr_clk_path, this);
+    src_clk_path = &src_clk_path1;
+  }
   const MinMax *src_clk_min_max =
     src_clk_path ? src_clk_path->minMax(this) : src_path->minMax(this);
   if (src_clk && tgt_clk
@@ -242,20 +251,30 @@ CheckCrpr::findCrpr(const PathVertex *src_clk_path,
   }
   const PathVertex *src_clk_path2 = src_clk_path1;
   const PathVertex *tgt_clk_path2 = tgt_clk_path1;
-  PathVertex tmp1, tmp2;
+  PathVertex src_prev, tgt_prev;
   // src_clk_path and tgt_clk_path are now in the same (gen)clk src path.
   // Use the vertex levels to back up the deeper path to see if they
   // overlap.
-  while (src_clk_path2 && tgt_clk_path2
-	 && src_clk_path2->pin(this) != tgt_clk_path2->pin(this)) {
-    Level src_level = src_clk_path2->vertex(this)->level();
-    Level tgt_level = tgt_clk_path2->vertex(this)->level();
-    if (src_level >= tgt_level)
-      src_clk_path2 = clkPathPrev(src_clk_path2, tmp1);
-    if (tgt_level >= src_level)
-      tgt_clk_path2 = clkPathPrev(tgt_clk_path2, tmp2);
+  int src_level = src_clk_path2->vertex(this)->level();
+  int tgt_level = tgt_clk_path2->vertex(this)->level();
+  while (src_clk_path2->pin(this) != tgt_clk_path2->pin(this)) {
+    int level_diff = src_level - tgt_level;
+    if (level_diff >= 0) {
+      clkPathPrev(src_clk_path2, src_prev);
+      if (src_prev.isNull())
+        break;
+      src_clk_path2 = &src_prev;
+      src_level = src_clk_path2->vertex(this)->level();
+    }
+    if (level_diff <= 0) {
+      clkPathPrev(tgt_clk_path2, tgt_prev);
+      if (tgt_prev.isNull())
+        break;
+      tgt_clk_path2 = &tgt_prev;
+      tgt_level = tgt_clk_path2->vertex(this)->level();
+    }
   }
-  if (src_clk_path2 && tgt_clk_path2
+  if (!src_clk_path2->isNull() && !tgt_clk_path2->isNull()
       && (src_clk_path2->transition(this) == tgt_clk_path2->transition(this)
 	  || same_pin)) {
     debugPrint(debug_, "crpr", 2, "crpr pin %s",
diff --git a/search/Crpr.hh b/search/Crpr.hh
index 62999a33..114a362c 100644
--- a/search/Crpr.hh
+++ b/search/Crpr.hh
@@ -56,8 +56,8 @@ public:
 			 int arrival_index);
 
 private:
-  PathVertex *clkPathPrev(const PathVertex *path,
-			  PathVertex &tmp);
+  void clkPathPrev(const PathVertex *path,
+                   PathVertex &prev);
   Arrival otherMinMaxArrival(const PathVertex *path);
   void checkCrpr1(const Path *src_path,
 		  const PathVertex *tgt_clk_path,
diff --git a/search/Search.cc b/search/Search.cc
index 0a22323e..9cc3d1df 100644
--- a/search/Search.cc
+++ b/search/Search.cc
@@ -2417,8 +2417,9 @@ Search::thruClkTag(PathVertex *from_path,
 		    && to_propagates_clk
 		    && (role->isWire()
 			|| role == TimingRole::combinational()));
-  ClkInfo *to_clk_info = thruClkInfo(from_path, from_clk_info,
-				     edge, to_vertex, to_pin, min_max, path_ap);
+  ClkInfo *to_clk_info = thruClkInfo(from_path, from_clk_info, from_is_clk,
+				     edge, to_pin, to_is_clk,
+                                     min_max, path_ap);
   Tag *to_tag = mutateTag(from_tag,from_pin,from_rf,from_is_clk,from_clk_info,
 			  to_pin, to_rf, to_is_clk, to_is_reg_clk, false,
 			  to_clk_info, nullptr, min_max, path_ap);
@@ -2429,9 +2430,10 @@ Search::thruClkTag(PathVertex *from_path,
 ClkInfo *
 Search::thruClkInfo(PathVertex *from_path,
 		    ClkInfo *from_clk_info,
+                    bool from_is_clk,
 		    Edge *edge,
-		    Vertex *to_vertex,
 		    const Pin *to_pin,
+                    bool to_is_clk,
 		    const MinMax *min_max,
 		    const PathAnalysisPt *path_ap)
 {
@@ -2462,7 +2464,7 @@ Search::thruClkInfo(PathVertex *from_path,
 
   PathVertex *to_crpr_clk_path = nullptr;
   if (sdc_->crprActive()
-      && to_vertex->isRegClk()) {
+      && from_is_clk && !to_is_clk) {
     to_crpr_clk_path = from_path;
     changed = true;
   }