diff --git a/src/runtime/c/pgf/db.cxx b/src/runtime/c/pgf/db.cxx
index 8f0bf4daa..068cccd4a 100644
--- a/src/runtime/c/pgf/db.cxx
+++ b/src/runtime/c/pgf/db.cxx
@@ -5,9 +5,9 @@
 
 #include "data.h"
 
-PGF_INTERNAL unsigned char* current_base = NULL;
-PGF_INTERNAL PgfDB* current_db = NULL;
-PGF_INTERNAL DB_scope *last_db_scope = NULL;
+PGF_INTERNAL __thread unsigned char* current_base __attribute__((tls_model("initial-exec"))) = NULL;
+PGF_INTERNAL __thread PgfDB* current_db __attribute__((tls_model("initial-exec"))) = NULL;
+PGF_INTERNAL __thread DB_scope *last_db_scope __attribute__((tls_model("initial-exec"))) = NULL;
 
 #ifndef DEFAULT_TOP_PAD
 #define DEFAULT_TOP_PAD        (0)
diff --git a/src/runtime/c/pgf/db.h b/src/runtime/c/pgf/db.h
index ddbe5a846..0331ad4b3 100644
--- a/src/runtime/c/pgf/db.h
+++ b/src/runtime/c/pgf/db.h
@@ -5,8 +5,8 @@
 
 class PgfDB;
 
-extern PGF_INTERNAL_DECL unsigned char* current_base;
-extern PGF_INTERNAL_DECL PgfDB*         current_db;
+extern PGF_INTERNAL_DECL __thread unsigned char* current_base __attribute__((tls_model("initial-exec")));
+extern PGF_INTERNAL_DECL __thread PgfDB*         current_db   __attribute__((tls_model("initial-exec")));
 
 struct malloc_state;
 
@@ -108,6 +108,6 @@ private:
     DB_scope* next_scope;
 };
 
-extern PGF_INTERNAL_DECL DB_scope *last_db_scope;
+extern PGF_INTERNAL_DECL thread_local DB_scope *last_db_scope __attribute__((tls_model("initial-exec")));
 
 #endif