diff --git a/lib/System/Unix/Program.cpp b/lib/System/Unix/Program.cpp
index 6943d52..ca8514d 100644
--- a/lib/System/Unix/Program.cpp
+++ b/lib/System/Unix/Program.cpp
@@ -24,6 +24,8 @@
 #include <sys/wait.h>
 #endif
 
+extern char** environ;
+
 namespace llvm {
 using namespace sys;
 
diff --git a/lib/System/Unix/Program.inc b/lib/System/Unix/Program.inc
index 6943d52..ca8514d 100644
--- a/lib/System/Unix/Program.inc
+++ b/lib/System/Unix/Program.inc
@@ -24,6 +24,8 @@
 #include <sys/wait.h>
 #endif
 
+extern char** environ;
+
 namespace llvm {
 using namespace sys;