diff --git a/mozilla/nsprpub/pr/src/md/mac/macio.c b/mozilla/nsprpub/pr/src/md/mac/macio.c
index f0e393bc14b..ae5aa2ffd3e 100644
--- a/mozilla/nsprpub/pr/src/md/mac/macio.c
+++ b/mozilla/nsprpub/pr/src/md/mac/macio.c
@@ -1044,6 +1044,12 @@ static OSErr CreateMacPathFromUnixPath(const char *unixPath, char **macPath)
 	char		*tgt;
 	OSErr		err = noErr;
 
+	PR_ASSERT(unixPath != nil);
+	if (nil == unixPath) {
+		err = paramErr;
+		goto exit;
+	}
+
 	// If unixPath is a zero-length string, we copy ":" into
 	// macPath, so we need a minimum of two bytes to handle
 	// the case of ":". 
@@ -1612,6 +1618,12 @@ static OSErr CreateMacPathFromUnixPath(const char *unixPath, char **macPath)
 	char		*tgt;
 	OSErr		err = noErr;
 
+	PR_ASSERT(unixPath != nil);
+	if (nil == unixPath) {
+		err = paramErr;
+		goto exit;
+	}
+
 	// If unixPath is a zero-length string, we copy ":" into
 	// macPath, so we need a minimum of two bytes to handle
 	// the case of ":".