3 files changed, 4 insertions, 0 deletions
diff --git a/src/libstore/globals.cc b/src/libstore/globals.cc
index 143260674d8c..d5615d93c7d0 100644
--- a/src/libstore/globals.cc
+++ b/src/libstore/globals.cc
@@ -67,6 +67,7 @@ Settings::Settings()
 
 void Settings::processEnvironment()
 {
+    nixPrefix = NIX_PREFIX;
     nixStore = canonPath(getEnv("NIX_STORE_DIR", getEnv("NIX_STORE", NIX_STORE_DIR)));
     nixDataDir = canonPath(getEnv("NIX_DATA_DIR", NIX_DATA_DIR));
     nixLogDir = canonPath(getEnv("NIX_LOG_DIR", NIX_LOG_DIR));
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 7add7cf7c523..60b11afe6088 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -42,6 +42,8 @@ struct Settings {
 
     Path nixDataDir; /* !!! fix */
 
+    Path nixPrefix;
+
     /* The directory where we log various operations. */
     Path nixLogDir;
 
diff --git a/src/libstore/local.mk b/src/libstore/local.mk
index 78b4d0fd4b94..771c06753a65 100644
--- a/src/libstore/local.mk
+++ b/src/libstore/local.mk
@@ -15,6 +15,7 @@ ifeq ($(OS), SunOS)
 endif
 
 libstore_CXXFLAGS = \
+ -DNIX_PREFIX=\"$(prefix)\" \
  -DNIX_STORE_DIR=\"$(storedir)\" \
  -DNIX_DATA_DIR=\"$(datadir)\" \
  -DNIX_STATE_DIR=\"$(localstatedir)/nix\" \