diff --git a/mgba-test-runner/add_cycles_register.patch b/mgba-test-runner/add_cycles_register.patch
new file mode 100644
index 0000000..5e767fe
--- /dev/null
+++ b/mgba-test-runner/add_cycles_register.patch
@@ -0,0 +1,40 @@
+diff --git a/include/mgba/internal/gba/io.h b/include/mgba/internal/gba/io.h
+index 9875061f3..bdeafdcd3 100644
+--- a/include/mgba/internal/gba/io.h
++++ b/include/mgba/internal/gba/io.h
+@@ -157,6 +157,7 @@ enum GBAIORegisters {
+ 	REG_DEBUG_STRING = 0xFFF600,
+ 	REG_DEBUG_FLAGS = 0xFFF700,
+ 	REG_DEBUG_ENABLE = 0xFFF780,
++	REG_DEBUG_CYCLES = 0xFFF800,
+ };
+ 
+ mLOG_DECLARE_CATEGORY(GBA_IO);
+diff --git a/src/gba/io.c b/src/gba/io.c
+index cc39e1192..d34dcb4b4 100644
+--- a/src/gba/io.c
++++ b/src/gba/io.c
+@@ -573,6 +573,11 @@ void GBAIOWrite(struct GBA* gba, uint32_t address, uint16_t value) {
+ 	case REG_DEBUG_ENABLE:
+ 		gba->debug = value == 0xC0DE;
+ 		return;
++	case REG_DEBUG_CYCLES: {
++		int32_t number_of_cycles = mTimingCurrentTime(&gba->timing);
++		mLOG(GBA_DEBUG, INFO, "Cycles: %d Tag: %hd", number_of_cycles, value);
++		return;
++	}
+ 	case REG_DEBUG_FLAGS:
+ 		if (gba->debug) {
+ 			GBADebug(gba, value);
+@@ -936,6 +941,11 @@ uint16_t GBAIORead(struct GBA* gba, uint32_t address) {
+ 			return 0x1DEA;
+ 		}
+ 		// Fall through
++	case REG_DEBUG_CYCLES: {
++		int32_t number_of_cycles = mTimingCurrentTime(&gba->timing);
++		mLOG(GBA_DEBUG, INFO, "Cycles: %d", number_of_cycles);
++		return number_of_cycles;
++	}
+ 	default:
+ 		mLOG(GBA_IO, GAME_ERROR, "Read from unused I/O register: %03X", address);
+ 		return GBALoadBad(gba->cpu);
diff --git a/mgba-test-runner/build-mgba.sh b/mgba-test-runner/build-mgba.sh
index 298a856..da488c5 100644
--- a/mgba-test-runner/build-mgba.sh
+++ b/mgba-test-runner/build-mgba.sh
@@ -2,12 +2,14 @@
 
 MGBA_VERSION=$1
 OUT_DIRECTORY=$2
+CURRENT_DIRECTORY=$(pwd)
 
 cd ${OUT_DIRECTORY}
 curl -L https://github.com/mgba-emu/mgba/archive/refs/tags/${MGBA_VERSION}.tar.gz -o mgba-${MGBA_VERSION}.tar.gz
 tar -xvf mgba-${MGBA_VERSION}.tar.gz
 cd mgba-${MGBA_VERSION}
 rm -rf build
+patch --strip=1 < ${CURRENT_DIRECTORY}/add_cycles_register.patch
 mkdir -p build
 cd build
 cmake .. \
diff --git a/mgba-test-runner/build.rs b/mgba-test-runner/build.rs
index 6d37341..086e8b9 100644
--- a/mgba-test-runner/build.rs
+++ b/mgba-test-runner/build.rs
@@ -29,4 +29,9 @@ fn main() {
     bindings
         .write_to_file(&out_path.join("runner-bindings.rs"))
         .expect("Couldn't write bindings!");
+
+    println!("cargo:rerun-if-changed=c/test-runner.c");
+    println!("cargo:rerun-if-changed=c/test-runner.h");
+    println!("cargo:rerun-if-changed=build-mgba.sh");
+    println!("cargo:rerun-if-changed=add_cycles_register.patch");
 }