diff --git a/v1/test/cases/testdata/v0/reachable/test-reachable-paths-0422.yaml b/v1/test/cases/testdata/v0/reachable/test-reachable-paths-0422.yaml
index 063d67870e..9b5917e87b 100644
--- a/v1/test/cases/testdata/v0/reachable/test-reachable-paths-0422.yaml
+++ b/v1/test/cases/testdata/v0/reachable/test-reachable-paths-0422.yaml
@@ -167,6 +167,37 @@ cases:
           - - a
             - c
 
+  - data: {}
+    input_term: '{
+        "graph": {
+          "1": [],
+          "2": ["1"],
+          "3": ["2"],
+          "4": ["3", "2"],
+          "5": ["4"]
+        },
+        "initial": ["5"]
+      }'
+    modules:
+      - |
+        package reachable
+
+        p = result {
+          graph.reachable_paths(input.graph, input.initial, result)
+        }
+    note: reachable_paths/shared_ancestor
+    query: data.reachable.p = x
+    want_result:
+      - x:
+          - - "5"
+            - "4"
+            - "2"
+            - "1"
+          - - "5"
+            - "4"
+            - "3"
+            - "2"
+            - "1"
   - data: {}
     input_term: '{
         "graph": {
diff --git a/v1/test/cases/testdata/v0/reachable/test-reachable-paths-1022.yaml b/v1/test/cases/testdata/v0/reachable/test-reachable-paths-1022.yaml
index a409cb5892..995c13d017 100644
--- a/v1/test/cases/testdata/v0/reachable/test-reachable-paths-1022.yaml
+++ b/v1/test/cases/testdata/v0/reachable/test-reachable-paths-1022.yaml
@@ -117,11 +117,14 @@ cases:
           - - one
             - five
             - six
+            - nine
 
           - - one
             - five
             - six
-            - nine
+            - seven
+            - eight
+            - three
 
           - - one
             - two
diff --git a/v1/test/cases/testdata/v1/reachable/test-reachable-paths-0422.yaml b/v1/test/cases/testdata/v1/reachable/test-reachable-paths-0422.yaml
index 193703bb96..6c281e5b1e 100644
--- a/v1/test/cases/testdata/v1/reachable/test-reachable-paths-0422.yaml
+++ b/v1/test/cases/testdata/v1/reachable/test-reachable-paths-0422.yaml
@@ -119,6 +119,28 @@ cases:
             - c
           - - a
             - c
+  - note: reachable_paths/shared_ancestor
+    query: data.reachable.p = x
+    modules:
+      - |
+        package reachable
+
+        p := result if {
+        	graph.reachable_paths(input.graph, input.initial, result)
+        }
+    data: {}
+    input_term: '{ "graph": { "1": [], "2": ["1"], "3": ["2"], "4": ["3", "2"], "5": ["4"] }, "initial": ["5"] }'
+    want_result:
+      - x:
+          - - "5"
+            - "4"
+            - "2"
+            - "1"
+          - - "5"
+            - "4"
+            - "3"
+            - "2"
+            - "1"
   - note: reachable_paths/invalid_end
     query: data.reachable.p = x
     modules:
diff --git a/v1/test/cases/testdata/v1/reachable/test-reachable-paths-1022.yaml b/v1/test/cases/testdata/v1/reachable/test-reachable-paths-1022.yaml
index 9eb8f359bf..6b0899c4c7 100644
--- a/v1/test/cases/testdata/v1/reachable/test-reachable-paths-1022.yaml
+++ b/v1/test/cases/testdata/v1/reachable/test-reachable-paths-1022.yaml
@@ -71,10 +71,13 @@ cases:
           - - one
             - five
             - six
+            - nine
           - - one
             - five
             - six
-            - nine
+            - seven
+            - eight
+            - three
           - - one
             - two
             - four
diff --git a/v1/topdown/reachable.go b/v1/topdown/reachable.go
index 1c31019db9..683c31c6c6 100644
--- a/v1/topdown/reachable.go
+++ b/v1/topdown/reachable.go
@@ -74,39 +74,31 @@ func builtinReachable(_ BuiltinContext, operands []*ast.Term, iter func(*ast.Ter
 
 // pathBuilder is called recursively to build a Set of paths that are reachable from the root
 func pathBuilder(graph ast.Object, root *ast.Term, path []*ast.Term, edgeRslt ast.Set, reached ast.Set) {
-	paths := []*ast.Term{}
-
-	if edges := graph.Get(root); edges != nil {
-		path = append(path, root)
-
-		if numberOfEdges(edges) >= 1 {
-
-			foreachVertex(edges, func(neighbor *ast.Term) {
-
-				if reached.Contains(neighbor) {
-					// If we've already reached this node, return current path (avoid infinite recursion)
-					paths = append(paths, path...)
-					edgeRslt.Add(ast.ArrayTerm(paths...))
-				} else {
-					reached.Add(root)
-					pathBuilder(graph, neighbor, path, edgeRslt, reached)
-
-				}
-
-			})
-
-		} else {
-			paths = append(paths, path...)
-			edgeRslt.Add(ast.ArrayTerm(paths...))
-
-		}
-	} else {
-		// Node is nonexistent (not in graph). Commit the current path (without adding this root)
-		paths = append(paths, path...)
-		edgeRslt.Add(ast.ArrayTerm(paths...))
-
+	edges := graph.Get(root)
+	if edges == nil {
+		// Node not in graph — commit path without this node.
+		edgeRslt.Add(ast.ArrayTerm(path...))
+		return
 	}
 
+	path = append(path, root)
+
+	if numberOfEdges(edges) == 0 {
+		edgeRslt.Add(ast.ArrayTerm(path...))
+		return
+	}
+
+	reached = reached.Copy()
+	reached.Add(root)
+
+	foreachVertex(edges, func(neighbor *ast.Term) {
+		if reached.Contains(neighbor) {
+			// Cycle detected — commit current path.
+			edgeRslt.Add(ast.ArrayTerm(path...))
+		} else {
+			pathBuilder(graph, neighbor, append([]*ast.Term(nil), path...), edgeRslt, reached)
+		}
+	})
 }
 
 func builtinReachablePaths(_ BuiltinContext, operands []*ast.Term, iter func(*ast.Term) error) error {