# Ninja does not detect source file changes
**URL:** https://discourse.kitware.com/t/ninja-does-not-detect-source-file-changes/1227
**Category:** Pulse Physiology Engine
**Created:** [February 27, 2024, 6:14am UTC](https://discourse.kitware.com/t/ninja-does-not-detect-source-file-changes/1227 "2024-02-27T06:14:16Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@di.sheng](https://discourse.kitware.com/u/di.sheng)
#### Post date: [February 27, 2024, 6:14am UTC](https://discourse.kitware.com/t/ninja-does-not-detect-source-file-changes/1227/1 "2024-02-27T06:14:16Z")
Hello,
I followed the instructions to do a dockcross build with ninja:
_# Run this command from a directory that contains both your sourc and your build directories_
\* docker run --rm dockcross/android-arm64 \> ./armv8a\* \*# This creates a file we will use to invoke our container\* \*# Next, set execution permissions\* \* chmod +x ./armv8a \*
_# Run CMake_
_# -B is the relative path to my build directory_
_# -H is the relative path to my Pulse source directory_
_./armv8a cmake -DPulse\_JAVA\_API:BOOL=OFF -B./Builds/pulse-engine-armv8a -H./Pulse/engine -GNinja\* \*# Use ninja to build (provided in the docker)\* \* ./armv8a ninja -C./Builds/pulse-engine-armv8a_
_# The PulseC.so for the target platform will be in the pulse-engine-armv8a/install/bin directory_
However, if I modify a source file such as PulseConfiguration.cpp and try to trigger a rebuild with ./armv8a ninja -C./Builds/pulse-engine-armv8a, the output is ninja: no work to do.
How to make sure the Ninja rebuilds? thank you.
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### Author:  [@abray](https://discourse.kitware.com/u/abray)
#### Post date: [February 27, 2024, 1:23pm UTC](https://discourse.kitware.com/t/ninja-does-not-detect-source-file-changes/1227/2 "2024-02-27T13:23:16Z")
Try
`./armv8a ninja -C./Builds/pulse-engine-armv8a/Innerbuild`