diff --git a/com.oracle.truffle.r.native/fficall/src/jni/Rembedded.c b/com.oracle.truffle.r.native/fficall/src/jni/Rembedded.c
index ef04a3a5ba61dc7392b03d127bde92a7562105d1..61431ad1d6d0b6c2717a6d7d17d8babc84c26456 100644
--- a/com.oracle.truffle.r.native/fficall/src/jni/Rembedded.c
+++ b/com.oracle.truffle.r.native/fficall/src/jni/Rembedded.c
@@ -526,6 +526,7 @@ static char *get_classpath(char *r_home) {
 				break;
 			} else {
 				bufptr += count;
+				max -= count;
 			}
 		}
 		close(pipefd[0]);