diff --git a/src/Scripting/NasalSys.cxx b/src/Scripting/NasalSys.cxx
index c25c3779c..bcc797e12 100644
--- a/src/Scripting/NasalSys.cxx
+++ b/src/Scripting/NasalSys.cxx
@@ -12,6 +12,7 @@
 
 #include <simgear/nasal/nasal.h>
 #include <simgear/props/props.hxx>
+#include <simgear/props/condition.hxx>
 #include <simgear/math/sg_random.h>
 #include <simgear/misc/sg_path.hxx>
 #include <simgear/misc/interpolator.hxx>
@@ -280,6 +281,24 @@ static naRef f_removelistener(naContext c, naRef me, int argc, naRef* args)
     return nasal->removeListener(c, argc, args);
 }
 
+// condition(property) extension function. Evaluates standard <condition>
+// (see $FG_ROOT/Docs/README.condition) and returns state.
+static naRef f_condition(naContext c, naRef me, int argc, naRef* args)
+{
+    SGPropertyNode* node;
+    naRef prop = argc > 0 ? args[0] : naNil();
+    if(naIsString(prop)) node = fgGetNode(naStr_data(prop), true);
+    else if(naIsGhost(prop)) node = *(SGPropertyNode_ptr*)naGhost_ptr(prop);
+    else {
+        naRuntimeError(c, "condition() with invalid property");
+        return naNil();
+    }
+    SGCondition *cond = sgReadCondition(globals->get_props(), node);
+    bool result = cond->test();
+    delete cond;
+    return naNum(result == true ? 1 : 0);
+}
+
 // Returns a ghost handle to the argument to the currently executing
 // command
 static naRef f_cmdarg(naContext c, naRef me, int argc, naRef* args)
@@ -356,6 +375,7 @@ static struct { char* name; naCFunction func; } funcs[] = {
     { "settimer",  f_settimer },
     { "_setlistener", f_setlistener },
     { "removelistener", f_removelistener },
+    { "_condition", f_condition },
     { "_cmdarg",  f_cmdarg },
     { "_interpolate",  f_interpolate },
     { "rand",  f_rand },