diff --git a/t/interop/interop-lib.sh b/t/interop/interop-lib.sh
index 3e0a2911d4..dea8883821 100644
--- a/t/interop/interop-lib.sh
+++ b/t/interop/interop-lib.sh
@@ -4,6 +4,10 @@
 . ../../GIT-BUILD-OPTIONS
 INTEROP_ROOT=$(pwd)
 BUILD_ROOT=$INTEROP_ROOT/build
+case "$PATH" in
+*\;*) PATH_SEP=\; ;;
+*) PATH_SEP=: ;;
+esac
 
 build_version () {
 	if test -z "$1"
@@ -57,7 +61,7 @@ wrap_git () {
 	write_script "$1" <<-EOF
 	GIT_EXEC_PATH="$2"
 	export GIT_EXEC_PATH
-	PATH="$2:\$PATH"
+	PATH="$2$PATH_SEP\$PATH"
 	export GIT_EXEC_PATH
 	exec git "\$@"
 	EOF
@@ -71,7 +75,7 @@ generate_wrappers () {
 	echo >&2 fatal: test tried to run generic git
 	exit 1
 	EOF
-	PATH=$(pwd)/.bin:$PATH
+	PATH=$(pwd)/.bin$PATH_SEP$PATH
 }
 
 VERSION_A=${GIT_TEST_VERSION_A:-$VERSION_A}
diff --git a/t/lib-proto-disable.sh b/t/lib-proto-disable.sh
index 83babe57d9..9dc55a83a0 100644
--- a/t/lib-proto-disable.sh
+++ b/t/lib-proto-disable.sh
@@ -214,7 +214,7 @@ setup_ext_wrapper () {
 		cd "$TRASH_DIRECTORY/remote" &&
 		eval "$*"
 		EOF
-		PATH=$TRASH_DIRECTORY:$PATH &&
+		PATH=$TRASH_DIRECTORY$PATH_SEP$PATH &&
 		export TRASH_DIRECTORY
 	'
 }
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index 308cd28f3b..47b152ac5c 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -5,7 +5,7 @@ test_description='blob conversion via gitattributes'
 . ./test-lib.sh
 
 TEST_ROOT="$PWD"
-PATH=$TEST_ROOT:$PATH
+PATH=$TEST_ROOT$PATH_SEP$PATH
 
 write_script <<\EOF "$TEST_ROOT/rot13.sh"
 tr \
diff --git a/t/t0060-path-utils.sh b/t/t0060-path-utils.sh
index cd74c0a471..6db9319ebf 100755
--- a/t/t0060-path-utils.sh
+++ b/t/t0060-path-utils.sh
@@ -135,25 +135,25 @@ ancestor /foo /fo -1
 ancestor /foo /foo -1
 ancestor /foo /bar -1
 ancestor /foo /foo/bar -1
-ancestor /foo /foo:/bar -1
-ancestor /foo /:/foo:/bar 0
-ancestor /foo /foo:/:/bar 0
-ancestor /foo /:/bar:/foo 0
+ancestor /foo "/foo$PATH_SEP/bar" -1
+ancestor /foo "/$PATH_SEP/foo$PATH_SEP/bar" 0
+ancestor /foo "/foo$PATH_SEP/$PATH_SEP/bar" 0
+ancestor /foo "/$PATH_SEP/bar$PATH_SEP/foo" 0
 ancestor /foo/bar / 0
 ancestor /foo/bar /fo -1
 ancestor /foo/bar /foo 4
 ancestor /foo/bar /foo/ba -1
-ancestor /foo/bar /:/fo 0
-ancestor /foo/bar /foo:/foo/ba 4
+ancestor /foo/bar "/$PATH_SEP/fo" 0
+ancestor /foo/bar "/foo$PATH_SEP/foo/ba" 4
 ancestor /foo/bar /bar -1
 ancestor /foo/bar /fo -1
-ancestor /foo/bar /foo:/bar 4
-ancestor /foo/bar /:/foo:/bar 4
-ancestor /foo/bar /foo:/:/bar 4
-ancestor /foo/bar /:/bar:/fo 0
-ancestor /foo/bar /:/bar 0
+ancestor /foo/bar "/foo$PATH_SEP/bar" 4
+ancestor /foo/bar "/$PATH_SEP/foo$PATH_SEP/bar" 4
+ancestor /foo/bar "/foo$PATH_SEP/$PATH_SEP/bar" 4
+ancestor /foo/bar "/$PATH_SEP/bar$PATH_SEP/fo" 0
+ancestor /foo/bar "/$PATH_SEP/bar" 0
 ancestor /foo/bar /foo 4
-ancestor /foo/bar /foo:/bar 4
+ancestor /foo/bar "/foo$PATH_SEP/bar" 4
 ancestor /foo/bar /bar -1
 
 test_expect_success 'strip_path_suffix' '
diff --git a/t/t0061-run-command.sh b/t/t0061-run-command.sh
index a51c2da8cc..0215c96944 100755
--- a/t/t0061-run-command.sh
+++ b/t/t0061-run-command.sh
@@ -47,7 +47,7 @@ test_expect_success 'run_command does not try to execute a directory' '
 	cat bin2/greet
 	EOF
 
-	PATH=$PWD/bin1:$PWD/bin2:$PATH \
+	PATH=$PWD/bin1$PATH_SEP$PWD/bin2$PATH_SEP$PATH \
 		test-tool run-command run-command greet >actual 2>err &&
 	test_cmp bin2/greet actual &&
 	test_must_be_empty err
@@ -64,7 +64,7 @@ test_expect_success POSIXPERM 'run_command passes over non-executable file' '
 	cat bin2/greet
 	EOF
 
-	PATH=$PWD/bin1:$PWD/bin2:$PATH \
+	PATH=$PWD/bin1$PATH_SEP$PWD/bin2$PATH_SEP$PATH \
 		test-tool run-command run-command greet >actual 2>err &&
 	test_cmp bin2/greet actual &&
 	test_must_be_empty err
@@ -84,7 +84,7 @@ test_expect_success POSIXPERM,SANITY 'unreadable directory in PATH' '
 	git config alias.nitfol "!echo frotz" &&
 	chmod a-rx local-command &&
 	(
-		PATH=./local-command:$PATH &&
+		PATH=./local-command$PATH_SEP$PATH &&
 		git nitfol >actual
 	) &&
 	echo frotz >expect &&
diff --git a/t/t0300-credentials.sh b/t/t0300-credentials.sh
index 82eaaea0f4..9391dc1fd1 100755
--- a/t/t0300-credentials.sh
+++ b/t/t0300-credentials.sh
@@ -30,7 +30,7 @@ test_expect_success 'setup helper scripts' '
 	test -z "$pass" || echo password=$pass
 	EOF
 
-	PATH="$PWD:$PATH"
+	PATH="$PWD$PATH_SEP$PATH"
 '
 
 test_expect_success 'credential_fill invokes helper' '
diff --git a/t/t1504-ceiling-dirs.sh b/t/t1504-ceiling-dirs.sh
index 3d51615e42..dc84733451 100755
--- a/t/t1504-ceiling-dirs.sh
+++ b/t/t1504-ceiling-dirs.sh
@@ -79,9 +79,9 @@ then
 	GIT_CEILING_DIRECTORIES="$TRASH_ROOT/top/"
 	test_fail subdir_ceil_at_top_slash
 
-	GIT_CEILING_DIRECTORIES=":$TRASH_ROOT/top"
+	GIT_CEILING_DIRECTORIES="$PATH_SEP$TRASH_ROOT/top"
 	test_prefix subdir_ceil_at_top_no_resolve "sub/dir/"
-	GIT_CEILING_DIRECTORIES=":$TRASH_ROOT/top/"
+	GIT_CEILING_DIRECTORIES="$PATH_SEP$TRASH_ROOT/top/"
 	test_prefix subdir_ceil_at_top_slash_no_resolve "sub/dir/"
 fi
 
@@ -111,13 +111,13 @@ GIT_CEILING_DIRECTORIES="$TRASH_ROOT/subdi"
 test_prefix subdir_ceil_at_subdi_slash "sub/dir/"
 
 
-GIT_CEILING_DIRECTORIES="/foo:$TRASH_ROOT/sub"
+GIT_CEILING_DIRECTORIES="/foo$PATH_SEP$TRASH_ROOT/sub"
 test_fail second_of_two
 
-GIT_CEILING_DIRECTORIES="$TRASH_ROOT/sub:/bar"
+GIT_CEILING_DIRECTORIES="$TRASH_ROOT/sub$PATH_SEP/bar"
 test_fail first_of_two
 
-GIT_CEILING_DIRECTORIES="/foo:$TRASH_ROOT/sub:/bar"
+GIT_CEILING_DIRECTORIES="/foo$PATH_SEP$TRASH_ROOT/sub$PATH_SEP/bar"
 test_fail second_of_three
 
 
diff --git a/t/t2300-cd-to-toplevel.sh b/t/t2300-cd-to-toplevel.sh
index c8de6d8a19..91f523d519 100755
--- a/t/t2300-cd-to-toplevel.sh
+++ b/t/t2300-cd-to-toplevel.sh
@@ -16,7 +16,7 @@ test_cd_to_toplevel () {
 	test_expect_success $3 "$2" '
 		(
 			cd '"'$1'"' &&
-			PATH="$EXEC_PATH:$PATH" &&
+			PATH="$EXEC_PATH$PATH_SEP$PATH" &&
 			. git-sh-setup &&
 			cd_to_toplevel &&
 			[ "$(pwd -P)" = "$TOPLEVEL" ]
diff --git a/t/t3402-rebase-merge.sh b/t/t3402-rebase-merge.sh
index a1ec501a87..d6220d9e7d 100755
--- a/t/t3402-rebase-merge.sh
+++ b/t/t3402-rebase-merge.sh
@@ -143,7 +143,7 @@ test_expect_success 'rebase -s funny -Xopt' '
 	git checkout -b test-funny master^ &&
 	test_commit funny &&
 	(
-		PATH=./test-bin:$PATH &&
+		PATH=./test-bin$PATH_SEP$PATH &&
 		git rebase -s funny -Xopt master
 	) &&
 	test -f funny.was.run
diff --git a/t/t3418-rebase-continue.sh b/t/t3418-rebase-continue.sh
index 25099d715c..1834e45085 100755
--- a/t/t3418-rebase-continue.sh
+++ b/t/t3418-rebase-continue.sh
@@ -60,7 +60,7 @@ test_expect_success 'rebase --continue remembers merge strategy and options' '
 	EOF
 	chmod +x test-bin/git-merge-funny &&
 	(
-		PATH=./test-bin:$PATH &&
+		PATH=./test-bin$PATH_SEP$PATH &&
 		test_must_fail git rebase -s funny -Xopt master topic
 	) &&
 	test -f funny.was.run &&
@@ -68,7 +68,7 @@ test_expect_success 'rebase --continue remembers merge strategy and options' '
 	echo "Resolved" >F2 &&
 	git add F2 &&
 	(
-		PATH=./test-bin:$PATH &&
+		PATH=./test-bin$PATH_SEP$PATH &&
 		git rebase --continue
 	) &&
 	test -f funny.was.run
@@ -92,7 +92,7 @@ test_expect_success 'rebase -i --continue handles merge strategy and options' '
 	EOF
 	chmod +x test-bin/git-merge-funny &&
 	(
-		PATH=./test-bin:$PATH &&
+		PATH=./test-bin$PATH_SEP$PATH &&
 		test_must_fail git rebase -i -s funny -Xopt -Xfoo master topic
 	) &&
 	test -f funny.was.run &&
@@ -100,7 +100,7 @@ test_expect_success 'rebase -i --continue handles merge strategy and options' '
 	echo "Resolved" >F2 &&
 	git add F2 &&
 	(
-		PATH=./test-bin:$PATH &&
+		PATH=./test-bin$PATH_SEP$PATH &&
 		git rebase --continue
 	) &&
 	test -f funny.was.run
diff --git a/t/t5615-alternate-env.sh b/t/t5615-alternate-env.sh
index b4905b822c..8ce5e99c3a 100755
--- a/t/t5615-alternate-env.sh
+++ b/t/t5615-alternate-env.sh
@@ -38,7 +38,7 @@ test_expect_success 'access alternate via absolute path' '
 '
 
 test_expect_success 'access multiple alternates' '
-	check_obj "$PWD/one.git/objects:$PWD/two.git/objects" <<-EOF
+	check_obj "$PWD/one.git/objects$PATH_SEP$PWD/two.git/objects" <<-EOF
 	$one blob
 	$two blob
 	EOF
@@ -74,7 +74,7 @@ test_expect_success 'access alternate via relative path (subdir)' '
 quoted='"one.git\057objects"'
 unquoted='two.git/objects'
 test_expect_success 'mix of quoted and unquoted alternates' '
-	check_obj "$quoted:$unquoted" <<-EOF
+	check_obj "$quoted$PATH_SEP$unquoted" <<-EOF
 	$one blob
 	$two blob
 	EOF
diff --git a/t/t5802-connect-helper.sh b/t/t5802-connect-helper.sh
index c6c2661878..a096eeeeb4 100755
--- a/t/t5802-connect-helper.sh
+++ b/t/t5802-connect-helper.sh
@@ -85,7 +85,7 @@ test_expect_success 'set up fake git-daemon' '
 		"$TRASH_DIRECTORY/remote"
 	EOF
 	export TRASH_DIRECTORY &&
-	PATH=$TRASH_DIRECTORY:$PATH
+	PATH=$TRASH_DIRECTORY$PATH_SEP$PATH
 '
 
 test_expect_success 'ext command can connect to git daemon (no vhost)' '
diff --git a/t/t7006-pager.sh b/t/t7006-pager.sh
index 00e09a375c..95a4d7ef5b 100755
--- a/t/t7006-pager.sh
+++ b/t/t7006-pager.sh
@@ -54,7 +54,7 @@ test_expect_success !MINGW,TTY 'LESS and LV envvars set by git-sh-setup' '
 		sane_unset LESS LV &&
 		PAGER="env >pager-env.out; wc" &&
 		export PAGER &&
-		PATH="$(git --exec-path):$PATH" &&
+		PATH="$(git --exec-path)$PATH_SEP$PATH" &&
 		export PATH &&
 		test_terminal sh -c ". git-sh-setup && git_pager"
 	) &&
@@ -388,7 +388,7 @@ test_default_pager() {
 		EOF
 		chmod +x \$less &&
 		(
-			PATH=.:\$PATH &&
+			PATH=.$PATH_SEP\$PATH &&
 			export PATH &&
 			$full_command
 		) &&
diff --git a/t/t7606-merge-custom.sh b/t/t7606-merge-custom.sh
index 8e8c4d7246..3c2c74ae6d 100755
--- a/t/t7606-merge-custom.sh
+++ b/t/t7606-merge-custom.sh
@@ -23,7 +23,7 @@ test_expect_success 'set up custom strategy' '
 	EOF
 
 	chmod +x git-merge-theirs &&
-	PATH=.:$PATH &&
+	PATH=.$PATH_SEP$PATH &&
 	export PATH
 '
 
diff --git a/t/t7811-grep-open.sh b/t/t7811-grep-open.sh
index d1ebfd88c7..414905be48 100755
--- a/t/t7811-grep-open.sh
+++ b/t/t7811-grep-open.sh
@@ -52,7 +52,7 @@ test_expect_success SIMPLEPAGER 'git grep -O' '
 	EOF
 	echo grep.h >expect.notless &&
 
-	PATH=.:$PATH git grep -O GREP_PATTERN >out &&
+	PATH=.$PATH_SEP$PATH git grep -O GREP_PATTERN >out &&
 	{
 		test_cmp expect.less pager-args ||
 		test_cmp expect.notless pager-args
diff --git a/t/t9003-help-autocorrect.sh b/t/t9003-help-autocorrect.sh
index b1c7919c4a..edcf912c9e 100755
--- a/t/t9003-help-autocorrect.sh
+++ b/t/t9003-help-autocorrect.sh
@@ -12,7 +12,7 @@ test_expect_success 'setup' '
 		echo distimdistim was called
 	EOF
 
-	PATH="$PATH:." &&
+	PATH="$PATH$PATH_SEP." &&
 	export PATH &&
 
 	git commit --allow-empty -m "a single log entry" &&
diff --git a/t/t9020-remote-svn.sh b/t/t9020-remote-svn.sh
index 76d9be2e1d..d81878d326 100755
--- a/t/t9020-remote-svn.sh
+++ b/t/t9020-remote-svn.sh
@@ -19,7 +19,7 @@ then
 fi
 
 # Override svnrdump with our simulator
-PATH="$HOME:$PATH"
+PATH="$HOME$PATH_SEP$PATH"
 export PATH PYTHON_PATH GIT_BUILD_DIR
 
 write_script "$HOME/svnrdump" <<\EOF
diff --git a/t/t9800-git-p4-basic.sh b/t/t9800-git-p4-basic.sh
index 5856563068..26aa039701 100755
--- a/t/t9800-git-p4-basic.sh
+++ b/t/t9800-git-p4-basic.sh
@@ -198,7 +198,7 @@ test_expect_success 'exit when p4 fails to produce marshaled output' '
 	EOF
 	chmod 755 badp4dir/p4 &&
 	(
-		PATH="$TRASH_DIRECTORY/badp4dir:$PATH" &&
+		PATH="$TRASH_DIRECTORY/badp4dir$PATH_SEP$PATH" &&
 		export PATH &&
 		test_expect_code 1 git p4 clone --dest="$git" //depot >errs 2>&1
 	) &&
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 9574627c15..af3169fd83 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -15,6 +15,15 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see http://www.gnu.org/licenses/ .
 
+# On Unix/Linux, the path separator is the colon, on other systems it
+# may be different, though. On Windows, for example, it is a semicolon.
+# If the PATH variable contains semicolons, it is pretty safe to assume
+# that the path separator is a semicolon.
+case "$PATH" in
+*\;*) PATH_SEP=\; ;;
+*) PATH_SEP=: ;;
+esac
+
 # Test the binaries we have just built.  The tests are kept in
 # t/ subdirectory and are run in 'trash directory' subdirectory.
 if test -z "$TEST_DIRECTORY"
@@ -1052,7 +1061,7 @@ then
 		done
 	done
 	IFS=$OLDIFS
-	PATH=$GIT_VALGRIND/bin:$PATH
+	PATH=$GIT_VALGRIND/bin$PATH_SEP$PATH
 	GIT_EXEC_PATH=$GIT_VALGRIND/bin
 	export GIT_VALGRIND
 	GIT_VALGRIND_MODE="$valgrind"
@@ -1064,7 +1073,7 @@ elif test -n "$GIT_TEST_INSTALLED"
 then
 	GIT_EXEC_PATH=$($GIT_TEST_INSTALLED/git --exec-path)  ||
 	error "Cannot run git from $GIT_TEST_INSTALLED."
-	PATH=$GIT_TEST_INSTALLED:$GIT_BUILD_DIR/t/helper:$PATH
+	PATH=$GIT_TEST_INSTALLED$PATH_SEP$GIT_BUILD_DIR/t/helper$PATH_SEP$PATH
 	GIT_EXEC_PATH=${GIT_TEST_EXEC_PATH:-$GIT_EXEC_PATH}
 else # normal case, use ../bin-wrappers only unless $with_dashes:
 	if test -n "$no_bin_wrappers"
@@ -1080,12 +1089,12 @@ else # normal case, use ../bin-wrappers only unless $with_dashes:
 			fi
 			with_dashes=t
 		fi
-		PATH="$git_bin_dir:$PATH"
+		PATH="$git_bin_dir$PATH_SEP$PATH"
 	fi
 	GIT_EXEC_PATH=$GIT_BUILD_DIR
 	if test -n "$with_dashes"
 	then
-		PATH="$GIT_BUILD_DIR:$GIT_BUILD_DIR/t/helper:$PATH"
+		PATH="$GIT_BUILD_DIR$PATH_SEP$GIT_BUILD_DIR/t/helper$PATH_SEP$PATH"
 	fi
 fi
 GIT_TEMPLATE_DIR="$GIT_BUILD_DIR"/templates/blt