diff --git a/gcc/testsuite/g++.dg/cpp1y/digit-sep-line-neg.C b/gcc/testsuite/g++.dg/cpp1y/digit-sep-line-neg.C
new file mode 100644
index 00000000000..fa3b1352109
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/digit-sep-line-neg.C
@@ -0,0 +1,4 @@
+// Test digit separators in #line (bug 82359).  Test invalid usage.
+// { dg-do preprocess { target c++14 } }
+
+#line 0''123 // { dg-error "is not a positive integer" }
diff --git a/gcc/testsuite/g++.dg/cpp1y/digit-sep-line.C b/gcc/testsuite/g++.dg/cpp1y/digit-sep-line.C
new file mode 100644
index 00000000000..48846e42221
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/digit-sep-line.C
@@ -0,0 +1,8 @@
+// Test digit separators in #line (bug 82359).
+// { dg-do compile { target c++14 } }
+
+#line 0'123
+static_assert (__LINE__ == 123, "#line with digit separator");
+
+#line 4'56'7'8'9
+static_assert (__LINE__ == 456789, "#line with digit separator");
diff --git a/libcpp/directives.c b/libcpp/directives.c
index f4aa17d1156..795f93e664b 100644
--- a/libcpp/directives.c
+++ b/libcpp/directives.c
@@ -922,12 +922,19 @@ strtolinenum (const uchar *str, size_t len, linenum_type *nump, bool *wrapped)
   linenum_type reg = 0;
 
   uchar c;
+  bool seen_digit_sep = false;
   *wrapped = false;
   while (len--)
     {
       c = *str++;
+      if (!seen_digit_sep && c == '\'' && len)
+	{
+	  seen_digit_sep = true;
+	  continue;
+	}
       if (!ISDIGIT (c))
 	return true;
+      seen_digit_sep = false;
       if (reg > ((linenum_type) -1) / 10)
 	*wrapped = true;
       reg *= 10;