diff --git a/libs/pbd/system_exec.cc b/libs/pbd/system_exec.cc
index 29bc11bb3b..0a17cce560 100644
--- a/libs/pbd/system_exec.cc
+++ b/libs/pbd/system_exec.cc
@@ -249,23 +249,22 @@ SystemExec::format_key_value_parameter (std::string key, std::string value)
 		start_pos += 1;
 	}
 
+#ifdef PLATFORM_WINDOWS
+	/* SystemExec::make_wargs() adds quotes around the complete argument
+	 * windows uses CreateProcess() with a parameter string
+	 * (and not an array list of separate arguments like Unix)
+	 * so quotes need to be escaped.
+	 */
 	start_pos = 0;
 	while((start_pos = v1.find("\"", start_pos)) != std::string::npos) {
 		v1.replace(start_pos, 1, "\\\"");
 		start_pos += 2;
 	}
-
-	size_t len = key.length() + v1.length() + 4;
-	char *mds = (char*) calloc(len, sizeof(char));
-#ifdef PLATFORM_WINDOWS
-	/* SystemExec::make_wargs() adds quotes around the complete argument
-	 * windows uses CreateProcess() with a parameter string
-	 * (and not an array list of separate arguments)
-	 */
-	snprintf(mds, len, "%s=%s", key.c_str(), v1.c_str());
-#else
-	snprintf(mds, len, "%s=\"%s\"", key.c_str(), v1.c_str());
 #endif
+
+	size_t len = key.length() + v1.length() + 2;
+	char *mds = (char*) calloc(len, sizeof(char));
+	snprintf(mds, len, "%s=%s", key.c_str(), v1.c_str());
 	return mds;
 }