diff --git a/tests/build.sh b/tests/build.sh
index ed84ec5..ddbe329 100755
--- a/tests/build.sh
+++ b/tests/build.sh
@@ -3,7 +3,7 @@ set -e
 ROOT=`pwd`
 
 if [ $# -ne 2 ]; then
-	echo "usage: ./build.sh [b|d] [path to cpp file]"
+	echo "usage: ./build.sh [b|d|c] [path to cpp file]"
 	exit 1
 fi
 
@@ -20,6 +20,8 @@ if [ $1 = "b" ]; then
 	FLAGS+=" -O2"
 elif [ $1 = "d" ]; then
 	FLAGS+=" -O0 -g -D_GLIBCXX_DEBUG -D_GLIBCXX_DEBUG_PEDANTIC -D_FORTIFY_SOURCE=2 -fsanitize=address,undefined"
+elif [ $1 = "c" ]; then
+	FLAGS+=" -O0 --coverage"
 else
 	echo "usage: ./build.sh [b|d] [path to cpp file]"
 	exit 1
diff --git a/tests/clear-coverage.sh b/tests/clear-coverage.sh
new file mode 100755
index 0000000..ec78b4c
--- /dev/null
+++ b/tests/clear-coverage.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+set -e -o pipefail
+
+find ../build/tests/ -name '*.gcda' -delete -or -name '*.gcno' -delete
+find ../build/tests/ -name '*.gcda' -or -name '*.gcno'
diff --git a/tests/own/test.sh b/tests/own/test.sh
index b589a63..1280eca 100755
--- a/tests/own/test.sh
+++ b/tests/own/test.sh
@@ -2,7 +2,7 @@
 set -e -o pipefail
 
 if [ $# -lt 3 ]; then
-    echo "usage: ./test.sh [b|d] [deterministic|fuzz|bench] [files...]"
+    echo "usage: ./test.sh [b|d|c] [deterministic|fuzz|bench] [files...]"
     exit 1
 fi
 
@@ -11,7 +11,10 @@ TEST_MODE=$2
 FILES=$(find ${@:3} -name '*.cpp' | sort)
 
 cd ..
-ROOT=`pwd`
+
+if [ $BUILD_MODE = "c" ]; then
+	./clear-coverage.sh
+fi
 
 for CPP_FILE in $FILES; do
     echo
@@ -20,5 +23,9 @@ for CPP_FILE in $FILES; do
     echo ================================================================
     ./build.sh $BUILD_MODE own/$CPP_FILE
     echo start
-    time $ROOT/../build/tests/own/$CPP_FILE.e $TEST_MODE
+    time ../build/tests/own/$CPP_FILE.e $TEST_MODE
 done
+
+if [ $BUILD_MODE = "c" ]; then
+	./report-coverage.sh
+fi
diff --git a/tests/report-coverage.sh b/tests/report-coverage.sh
new file mode 100755
index 0000000..efb1df4
--- /dev/null
+++ b/tests/report-coverage.sh
@@ -0,0 +1,7 @@
+#!/bin/bash
+set -e -o pipefail
+
+mkdir -p ../build/coverage
+gcovr --root ../src/ --object-directory ../build/  \
+      --html-details ../build/coverage/index.html  \
+      --html-tab-size=2 --merge-mode-functions=separate
diff --git a/tests/yosupo/test.sh b/tests/yosupo/test.sh
index 9805f56..b98fdec 100755
--- a/tests/yosupo/test.sh
+++ b/tests/yosupo/test.sh
@@ -2,7 +2,7 @@
 set -e -o pipefail
 
 if [ $# -lt 2 ]; then
-    echo "usage: ./test.sh [b|d] [files...]"
+    echo "usage: ./test.sh [b|d|c] [files...]"
     exit 1
 fi
 
@@ -12,6 +12,10 @@ FILES=$(find ${@:2} -name '*.cpp' | sort)
 cd ..
 ROOT=`pwd`
 
+# if [ $BUILD_MODE = "c" ]; then
+# 	./clear-coverage.sh
+# fi
+
 for CPP_FILE in $FILES; do
 	echo
 	echo ================================================================
@@ -44,3 +48,7 @@ for CPP_FILE in $FILES; do
 		fi
 	done
 done
+
+if [ $BUILD_MODE = "c" ]; then
+	./report-coverage.sh
+fi