diff --git a/libraries/AP_Math/AP_Math.cpp b/libraries/AP_Math/AP_Math.cpp
index 887a6747b6..a2951c9665 100644
--- a/libraries/AP_Math/AP_Math.cpp
+++ b/libraries/AP_Math/AP_Math.cpp
@@ -305,3 +305,12 @@ bool rotation_equal(enum Rotation r1, enum Rotation r2)
     return (v1 - v2).length() < 0.001;
 }
 
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+// fill an array of float with NaN, used to invalidate memory in SITL
+void fill_nanf(float *f, uint16_t count)
+{
+    while (count--) {
+        *f++ = std::numeric_limits<float>::signaling_NaN();
+    }
+}
+#endif
diff --git a/libraries/AP_Math/AP_Math.h b/libraries/AP_Math/AP_Math.h
index 3f841ceba9..feff4f1afb 100644
--- a/libraries/AP_Math/AP_Math.h
+++ b/libraries/AP_Math/AP_Math.h
@@ -274,3 +274,8 @@ bool is_valid_octal(uint16_t octal) WARN_IF_UNUSED;
 
 // return true if two rotations are equal
 bool rotation_equal(enum Rotation r1, enum Rotation r2) WARN_IF_UNUSED;
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
+// fill an array of float with NaN, used to invalidate memory in SITL
+void fill_nanf(float *f, uint16_t count);
+#endif