diff --git a/src/smt/CMakeLists.txt b/src/smt/CMakeLists.txt
index 04aadac54..add3f1ba7 100644
--- a/src/smt/CMakeLists.txt
+++ b/src/smt/CMakeLists.txt
@@ -66,7 +66,6 @@ z3_add_component(smt
     theory_lra.cpp
     theory_nseq.cpp
     nseq_state.cpp
-    nseq_regex.cpp
     nseq_model.cpp
     theory_opt.cpp
     theory_pb.cpp
diff --git a/src/smt/nseq_model.cpp b/src/smt/nseq_model.cpp
index 8eb8d5a59..6fd9779b1 100644
--- a/src/smt/nseq_model.cpp
+++ b/src/smt/nseq_model.cpp
@@ -17,7 +17,7 @@ Author:
 --*/
 #include "smt/nseq_model.h"
 #include "smt/theory_nseq.h"
-#include "smt/nseq_regex.h"
+#include "smt/seq/nseq_regex.h"
 #include "smt/nseq_state.h"
 #include "smt/smt_context.h"
 #include "smt/smt_model_generator.h"
diff --git a/src/smt/seq/CMakeLists.txt b/src/smt/seq/CMakeLists.txt
index e6ed34c34..faa3a1ec7 100644
--- a/src/smt/seq/CMakeLists.txt
+++ b/src/smt/seq/CMakeLists.txt
@@ -1,5 +1,6 @@
 z3_add_component(smt_seq
   SOURCES
+    nseq_regex.cpp
     seq_parikh.cpp
     seq_nielsen.cpp
   COMPONENT_DEPENDENCIES
diff --git a/src/smt/nseq_regex.cpp b/src/smt/seq/nseq_regex.cpp
similarity index 99%
rename from src/smt/nseq_regex.cpp
rename to src/smt/seq/nseq_regex.cpp
index 743b74ef6..e62843bb7 100644
--- a/src/smt/nseq_regex.cpp
+++ b/src/smt/seq/nseq_regex.cpp
@@ -14,7 +14,7 @@ Author:
     Nikolaj Bjorner (nbjorner) 2026-03-01
 
 --*/
-#include "smt/nseq_regex.h"
+#include "smt/seq/nseq_regex.h"
 #include <unordered_set>
 
 namespace smt {
diff --git a/src/smt/nseq_regex.h b/src/smt/seq/nseq_regex.h
similarity index 100%
rename from src/smt/nseq_regex.h
rename to src/smt/seq/nseq_regex.h
diff --git a/src/smt/seq/seq_nielsen.cpp b/src/smt/seq/seq_nielsen.cpp
index 52d3ec36b..45352e747 100644
--- a/src/smt/seq/seq_nielsen.cpp
+++ b/src/smt/seq/seq_nielsen.cpp
@@ -21,7 +21,7 @@ Author:
 
 #include "smt/seq/seq_nielsen.h"
 #include "smt/seq/seq_parikh.h"
-#include "smt/nseq_regex.h"
+#include "smt/seq/nseq_regex.h"
 #include "ast/arith_decl_plugin.h"
 #include "ast/ast_pp.h"
 #include "ast/rewriter/seq_rewriter.h"
diff --git a/src/smt/seq/seq_nielsen.h b/src/smt/seq/seq_nielsen.h
index 987350924..11f594098 100644
--- a/src/smt/seq/seq_nielsen.h
+++ b/src/smt/seq/seq_nielsen.h
@@ -245,7 +245,7 @@ Author:
 #include "model/model.h"
 
 namespace smt {
-    class nseq_regex;  // forward declaration (defined in smt/nseq_regex.h)
+    class nseq_regex;  // forward declaration (defined in smt/seq/nseq_regex.h)
 }
 
 namespace seq {
diff --git a/src/smt/theory_nseq.h b/src/smt/theory_nseq.h
index 24f5ad566..bd1dd961c 100644
--- a/src/smt/theory_nseq.h
+++ b/src/smt/theory_nseq.h
@@ -26,7 +26,7 @@ Author:
 #include "smt/smt_arith_value.h"
 #include "smt/seq/seq_nielsen.h"
 #include "smt/nseq_state.h"
-#include "smt/nseq_regex.h"
+#include "smt/seq/nseq_regex.h"
 #include "smt/nseq_model.h"
 #include "smt/nseq_context_solver.h"
 
diff --git a/src/test/nseq_regex.cpp b/src/test/nseq_regex.cpp
index 6970413b0..8d9533005 100644
--- a/src/test/nseq_regex.cpp
+++ b/src/test/nseq_regex.cpp
@@ -15,7 +15,7 @@ Abstract:
 #include "ast/reg_decl_plugins.h"
 #include "ast/euf/euf_egraph.h"
 #include "ast/euf/euf_sgraph.h"
-#include "smt/nseq_regex.h"
+#include "smt/seq/nseq_regex.h"
 #include "smt/seq/seq_nielsen.h"
 #include "util/lbool.h"
 #include "util/zstring.h"