diff --git a/src/libei.c b/src/libei.c
index ed24ea0..623cc25 100644
--- a/src/libei.c
+++ b/src/libei.c
@@ -113,19 +113,8 @@ DEFINE_UNREF_CLEANUP_FUNC(ei_region);
 static void
 set_prop_cmdline(struct ei *ei)
 {
-	char path[PATH_MAX];
-
-	xsnprintf(path, sizeof(path), "/proc/%d/cmdline", getpid());
-	_cleanup_close_ int fd = open(path, O_RDONLY);
-	if (fd < 0)
-		return;
-
-	int len;
-	if ((len = read(fd, path, sizeof(path) - 1)) < 0)
-		return;
-	path[len] = '\0';
-
-	ei_property_update(ei, "ei.application.cmdline", path, EI_PROPERTY_PERM_NONE);
+	_cleanup_free_ char *cmdline = cmdline_as_str();
+	ei_property_update(ei, "ei.application.cmdline", cmdline, EI_PROPERTY_PERM_NONE);
 }
 
 static void
diff --git a/src/util-strings.c b/src/util-strings.c
index 758c97d..486f2dc 100644
--- a/src/util-strings.c
+++ b/src/util-strings.c
@@ -471,4 +471,22 @@ MUNIT_TEST(test_strreplace)
 
 	return MUNIT_OK;
 }
+
+MUNIT_TEST(test_cmdline_as_str)
+{
+	_cleanup_free_ char *from_function = cmdline_as_str();
+	char cmdline[PATH_MAX];
+
+	xsnprintf(cmdline, sizeof(cmdline), "/proc/%i/cmdline", getpid());
+
+	int fd = open(cmdline, O_RDONLY);
+	munit_assert_int(fd, >=, 0);
+	int len = read(fd, cmdline, sizeof(cmdline) - 1);
+	munit_assert_int(len, >=, 0);
+	cmdline[len] = '\0';
+
+	munit_assert_string_equal(cmdline, from_function);
+
+	return MUNIT_OK;
+}
 #endif
diff --git a/src/util-strings.h b/src/util-strings.h
index 0758e24..5e257f7 100644
--- a/src/util-strings.h
+++ b/src/util-strings.h
@@ -30,6 +30,7 @@
 #include <assert.h>
 #include <ctype.h>
 #include <errno.h>
+#include <fcntl.h>
 #include <limits.h>
 #include <math.h>
 #include <string.h>
@@ -380,3 +381,19 @@ strstartswith(const char *str, const char *prefix)
 
 	return prefixlen > 0 ? strneq(str, prefix, strlen(prefix)) : false;
 }
+
+/**
+ * Return the content of /proc/$pid/cmdline as newly allocated string.
+ */
+static inline char *
+cmdline_as_str(void)
+{
+	int fd = open("/proc/self/cmdline", O_RDONLY);
+	if (fd > 0) {
+		char buffer[1024] = {0};
+		int len = read(fd, buffer, sizeof(buffer) - 1);
+		close(fd);
+		return len > 0 ? xstrdup(buffer) : NULL;
+	}
+	return NULL;
+}
diff --git a/test/test-ei.c b/test/test-ei.c
index 8272d12..bde7bc7 100644
--- a/test/test-ei.c
+++ b/test/test-ei.c
@@ -54,16 +54,9 @@ MUNIT_TEST(test_ei_initial_properties)
 {
 	_unref_(peck) *peck = peck_new();
 	char pid[64];
-	char cmdline[PATH_MAX];
+	_cleanup_free_ char *cmdline = cmdline_as_str();
 
 	xsnprintf(pid, sizeof(pid), "%i", getpid());
-	xsnprintf(cmdline, sizeof(cmdline), "/proc/%i/cmdline", getpid());
-
-	int fd = open(cmdline, O_RDONLY);
-	munit_assert_int(fd, >=, 0);
-	int len = read(fd, cmdline, sizeof(cmdline) - 1);
-	munit_assert_int(len, >=, 0);
-	cmdline[len] = '\0';
 
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_NONE);
 	peck_dispatch_until_stable(peck);
diff --git a/tools/eis-fake-impl-portal.c b/tools/eis-fake-impl-portal.c
index d235a56..9843e13 100644
--- a/tools/eis-fake-impl-portal.c
+++ b/tools/eis-fake-impl-portal.c
@@ -189,19 +189,8 @@ portal_create_session(sd_bus_message *m, void *userdata,
 static void
 set_prop_cmdline(struct reis *reis)
 {
-	char path[PATH_MAX];
-
-	xsnprintf(path, sizeof(path), "/proc/%i/cmdline", getpid());
-	_cleanup_close_ int fd = open(path, O_RDONLY);
-	if (fd < 0)
-		return;
-
-	int len;
-	if ((len = read(fd, path, sizeof(path) - 1)) < 0)
-		return;
-	path[len] = '\0';
-
-	reis_set_property_with_permissions(reis, "ei.application.cmdline", path, REIS_PROPERTY_PERM_NONE);
+	_cleanup_free_ char *cmdline = cmdline_as_str();
+	reis_set_property_with_permissions(reis, "ei.application.cmdline", cmdline, REIS_PROPERTY_PERM_NONE);
 }
 
 static void
diff --git a/tools/eis-fake-portal.c b/tools/eis-fake-portal.c
index 8503bcb..abfdf75 100644
--- a/tools/eis-fake-portal.c
+++ b/tools/eis-fake-portal.c
@@ -230,19 +230,8 @@ portal_create_session(sd_bus_message *m, void *userdata,
 static void
 set_prop_cmdline(struct reis *reis)
 {
-	char path[PATH_MAX];
-
-	xsnprintf(path, sizeof(path), "/proc/%i/cmdline", getpid());
-	_cleanup_close_ int fd = open(path, O_RDONLY);
-	if (fd < 0)
-		return;
-
-	int len;
-	if ((len = read(fd, path, sizeof(path) - 1)) < 0)
-		return;
-	path[len] = '\0';
-
-	reis_set_property_with_permissions(reis, "ei.application.cmdline", path, REIS_PROPERTY_PERM_NONE);
+	_cleanup_free_ char *cmdline = cmdline_as_str();
+	reis_set_property_with_permissions(reis, "ei.application.cmdline", cmdline, REIS_PROPERTY_PERM_NONE);
 }
 
 static void