diff --git a/core/parse-xml.cpp b/core/parse-xml.cpp
index dd3c3aa75..0383a92a6 100644
--- a/core/parse-xml.cpp
+++ b/core/parse-xml.cpp
@@ -2256,42 +2256,20 @@ extern "C" int parse_dlf_buffer(unsigned char *buffer, size_t size, struct divel
 
 	/* Recording the starting battery status to extra data */
 	if (battery_start.volt1) {
-		size_t stringsize = snprintf(NULL, 0, "%dmV (%d%%)", battery_start.volt1, battery_start.percent1) + 1;
-		char *ptr = (char *)malloc(stringsize);
+		std::string str = format_string_std("%dmV (%d%%)", battery_start.volt1, battery_start.percent1);
+		add_extra_data(state.cur_dc, "Battery 1 (start)", str.c_str());
 
-		if (ptr) {
-			snprintf(ptr, stringsize, "%dmV (%d%%)", battery_start.volt1, battery_start.percent1);
-			add_extra_data(state.cur_dc, "Battery 1 (start)", ptr);
-			free(ptr);
-		}
-
-		stringsize = snprintf(NULL, 0, "%dmV (%d%%)", battery_start.volt2, battery_start.percent2) + 1;
-		ptr = (char *)malloc(stringsize);
-		if (ptr) {
-			snprintf(ptr, stringsize, "%dmV (%d%%)", battery_start.volt2, battery_start.percent2);
-			add_extra_data(state.cur_dc, "Battery 2 (start)", ptr);
-			free(ptr);
-		}
+		str = format_string_std("%dmV (%d%%)", battery_start.volt2, battery_start.percent2);
+		add_extra_data(state.cur_dc, "Battery 2 (start)", str.c_str());
 	}
 
 	/* Recording the ending battery status to extra data */
 	if (battery_end.volt1) {
-		size_t stringsize = snprintf(NULL, 0, "%dmV (%d%%)", battery_end.volt1, battery_end.percent1) + 1;
-		char *ptr = (char *)malloc(stringsize);
+		std::string str = format_string_std("%dmV (%d%%)", battery_end.volt1, battery_end.percent1);
+		add_extra_data(state.cur_dc, "Battery 1 (end)", str.c_str());
 
-		if (ptr) {
-			snprintf(ptr, stringsize, "%dmV (%d%%)", battery_end.volt1, battery_end.percent1);
-			add_extra_data(state.cur_dc, "Battery 1 (end)", ptr);
-			free(ptr);
-		}
-
-		stringsize = snprintf(NULL, 0, "%dmV (%d%%)", battery_end.volt2, battery_end.percent2) + 1;
-		ptr = (char *)malloc(stringsize);
-		if (ptr) {
-			snprintf(ptr, stringsize, "%dmV (%d%%)", battery_end.volt2, battery_end.percent2);
-			add_extra_data(state.cur_dc, "Battery 2 (end)", ptr);
-			free(ptr);
-		}
+		str = format_string_std("%dmV (%d%%)", battery_end.volt2, battery_end.percent2);
+		add_extra_data(state.cur_dc, "Battery 2 (end)", str.c_str());
 	}
 
 	divecomputer_end(&state);
diff --git a/core/subsurface-string.h b/core/subsurface-string.h
index e2127d02c..582f7622b 100644
--- a/core/subsurface-string.h
+++ b/core/subsurface-string.h
@@ -60,5 +60,21 @@ extern double strtod_flags(const char *str, const char **ptr, unsigned int flags
 
 #ifdef __cplusplus
 }
+
+#include <string>
+template <class... Args>
+std::string format_string_std(const char *fmt, Args&&... args)
+{
+	size_t stringsize = snprintf(NULL, 0, fmt, std::forward<Args>(args)...);
+	if (stringsize == 0)
+		return std::string();
+	std::string res;
+	res.resize(stringsize); // Pointless clearing, oh my.
+	// This overwrites the terminal null-byte of std::string.
+	// That's probably "undefined behavior". Oh my.
+	snprintf(res.data(), stringsize + 1, fmt, std::forward<Args>(args)...);
+	return res;
+}
+
 #endif
 #endif // SUBSURFACE_STRING_H