diff --git a/src/ast/euf/euf_ac_plugin.h b/src/ast/euf/euf_ac_plugin.h
index ea444b60c..3c937ed5c 100644
--- a/src/ast/euf/euf_ac_plugin.h
+++ b/src/ast/euf/euf_ac_plugin.h
@@ -137,7 +137,7 @@ namespace euf {
             }
         };
 
-        unsigned                 m_fid = 0;
+        theory_id                m_fid = 0;
         unsigned                 m_op = null_decl_kind;
         func_decl*               m_decl = nullptr;
         vector<eq>               m_eqs;
@@ -273,7 +273,7 @@ namespace euf {
 
         ~ac_plugin() override {}
         
-        unsigned get_id() const override { return m_fid; }
+        theory_id get_id() const override { return m_fid; }
 
         void register_node(enode* n) override;
 
diff --git a/src/ast/euf/euf_arith_plugin.h b/src/ast/euf/euf_arith_plugin.h
index 7cca01f1c..a31c80a70 100644
--- a/src/ast/euf/euf_arith_plugin.h
+++ b/src/ast/euf/euf_arith_plugin.h
@@ -35,7 +35,7 @@ namespace euf {
 
         ~arith_plugin() override {}
 
-        unsigned get_id() const override { return a.get_family_id(); }
+        theory_id get_id() const override { return a.get_family_id(); }
 
         void register_node(enode* n) override;
 
diff --git a/src/ast/euf/euf_bv_plugin.h b/src/ast/euf/euf_bv_plugin.h
index f8c01af49..ec2c0b448 100644
--- a/src/ast/euf/euf_bv_plugin.h
+++ b/src/ast/euf/euf_bv_plugin.h
@@ -97,7 +97,7 @@ namespace euf {
 
         ~bv_plugin() override {}
 
-        unsigned get_id() const override { return bv.get_family_id(); }
+        theory_id get_id() const override { return bv.get_family_id(); }
 
         void register_node(enode* n) override;
 
diff --git a/src/ast/euf/euf_plugin.h b/src/ast/euf/euf_plugin.h
index ff49d6c40..8dbd4d7e7 100644
--- a/src/ast/euf/euf_plugin.h
+++ b/src/ast/euf/euf_plugin.h
@@ -40,7 +40,7 @@ namespace euf {
 
         virtual ~plugin() {}
 
-        virtual unsigned get_id() const = 0;
+        virtual theory_id get_id() const = 0;
 
         virtual void register_node(enode* n) = 0;
         
diff --git a/src/ast/euf/euf_specrel_plugin.h b/src/ast/euf/euf_specrel_plugin.h
index 228bb5e15..ae93bd2a5 100644
--- a/src/ast/euf/euf_specrel_plugin.h
+++ b/src/ast/euf/euf_specrel_plugin.h
@@ -37,7 +37,7 @@ namespace euf {
 
         ~specrel_plugin() override {}
         
-        unsigned get_id() const override { return sp.get_family_id(); }
+        theory_id get_id() const override { return sp.get_family_id(); }
 
         void register_node(enode* n) override;