diff --git a/.gitignore b/.gitignore
index b3b13694af..517022399b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -166,6 +166,10 @@ uptime-*.json
 /src/ext/keccak-tiny/libkeccak-tiny.a
 /src/ext/keccak-tiny/libkeccak-tiny.lib
 
+# /src/lib
+/src/lib/libtor-err.a
+/src/lib/libtor-err-testing.a
+
 # /src/or/
 /src/or/Makefile
 /src/or/Makefile.in
diff --git a/Makefile.am b/Makefile.am
index 579b9a089c..6c60de111c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -40,12 +40,14 @@ endif
 # "Common" libraries used to link tor's utility code.
 TOR_UTIL_LIBS = \
 	src/common/libor.a \
+        src/lib/libtor-err.a \
 	src/common/libor-ctime.a
 
 # Variants of the above for linking the testing variant of tor (for coverage
 # and tests)
 TOR_UTIL_TESTING_LIBS = \
 	src/common/libor-testing.a \
+        src/lib/libtor-err-testing.a \
 	src/common/libor-ctime-testing.a
 
 # Internal crypto libraries used in Tor
diff --git a/src/common/include.am b/src/common/include.am
index 8afec9c054..5337034861 100644
--- a/src/common/include.am
+++ b/src/common/include.am
@@ -82,7 +82,6 @@ src_common_libor_ctime_testing_a_CFLAGS = @CFLAGS_CONSTTIME@ $(TEST_CFLAGS)
 LIBOR_A_SRC = \
   src/common/address.c					\
   src/common/address_set.c				\
-  src/common/backtrace.c				\
   src/common/buffers.c					\
   src/common/compat.c					\
   src/common/compat_threads.c				\
@@ -99,7 +98,6 @@ LIBOR_A_SRC = \
   src/common/sandbox.c					\
   src/common/storagedir.c				\
   src/common/token_bucket.c				\
-  src/common/torerr.c					\
   src/common/workqueue.c				\
   $(libor_extra_source)					\
   $(threads_impl_source)				\
@@ -161,7 +159,6 @@ src_common_libor_event_testing_a_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
 COMMONHEADERS = \
   src/common/address.h				\
   src/common/address_set.h			\
-  src/common/backtrace.h			\
   src/common/buffers.h				\
   src/common/buffers_tls.h			\
   src/common/aes.h				\
@@ -203,7 +200,6 @@ COMMONHEADERS = \
   src/common/testsupport.h			\
   src/common/timers.h				\
   src/common/token_bucket.h			\
-  src/common/torerr.h				\
   src/common/torint.h				\
   src/common/torlog.h				\
   src/common/tortls.h				\
diff --git a/src/include.am b/src/include.am
index 90ecf90d45..424481485f 100644
--- a/src/include.am
+++ b/src/include.am
@@ -1,6 +1,7 @@
 include src/ext/include.am
-include src/trunnel/include.am
+include src/lib/err/include.am
 include src/common/include.am
+include src/trunnel/include.am
 include src/or/include.am
 include src/rust/include.am
 include src/test/include.am
diff --git a/src/common/backtrace.c b/src/lib/err/backtrace.c
similarity index 100%
rename from src/common/backtrace.c
rename to src/lib/err/backtrace.c
diff --git a/src/common/backtrace.h b/src/lib/err/backtrace.h
similarity index 100%
rename from src/common/backtrace.h
rename to src/lib/err/backtrace.h
diff --git a/src/lib/err/include.am b/src/lib/err/include.am
new file mode 100644
index 0000000000..257ba3004b
--- /dev/null
+++ b/src/lib/err/include.am
@@ -0,0 +1,17 @@
+
+noinst_LIBRARIES += src/lib/libtor-err.a
+
+if UNITTESTS_ENABLED
+noinst_LIBRARIES += src/lib/libtor-err-testing.a
+endif
+
+src_lib_libtor_err_a_SOURCES =			\
+	src/lib/err/backtrace.c				\
+	src/lib/err/torerr.c
+
+src_lib_libtor_err_testing_a_SOURCES = \
+	$(src_lib_libtor_err_a_SOURCES)
+
+noinst_HEADERS +=					\
+	src/lib/err/backtrace.h				\
+	src/lib/err/torerr.h
diff --git a/src/common/torerr.c b/src/lib/err/torerr.c
similarity index 100%
rename from src/common/torerr.c
rename to src/lib/err/torerr.c
diff --git a/src/common/torerr.h b/src/lib/err/torerr.h
similarity index 100%
rename from src/common/torerr.h
rename to src/lib/err/torerr.h
diff --git a/src/rust/build.rs b/src/rust/build.rs
index b943aa5535..32000b12f5 100644
--- a/src/rust/build.rs
+++ b/src/rust/build.rs
@@ -138,9 +138,9 @@ pub fn main() {
             cfg.from_cflags("TOR_LDFLAGS_openssl");
             cfg.from_cflags("TOR_LDFLAGS_libevent");
 
+            cfg.link_relpath("src/lib");
             cfg.link_relpath("src/common");
             cfg.link_relpath("src/ext/keccak-tiny");
-            cfg.link_relpath("src/ext/keccak-tiny");
             cfg.link_relpath("src/ext/ed25519/ref10");
             cfg.link_relpath("src/ext/ed25519/donna");
             cfg.link_relpath("src/trunnel");
@@ -152,6 +152,7 @@ pub fn main() {
             cfg.component("or-crypto-testing");
             cfg.component("or-ctime-testing");
             cfg.component("or-testing");
+            cfg.component("tor-err-testing");
             cfg.component("or-event-testing");
             cfg.component("or-ctime-testing");
             cfg.component("curve25519_donna");