diff --git a/range-mappings-proposal-tests.json b/range-mappings-proposal-tests.json
index 42d47d5..7b108e7 100644
--- a/range-mappings-proposal-tests.json
+++ b/range-mappings-proposal-tests.json
@@ -36,6 +36,13 @@
       "sourceMapFile": "invalid-base64-char-2.js.map",
       "sourceMapIsValid": false
     },
+    {
+      "name": "rangeMappingsInvalidVLQZero",
+      "description": "VLQ of zero is invalid because offsets are 1-based",
+      "baseFile": "invalid-vlq-zero.js",
+      "sourceMapFile": "invalid-vlq-zero.js.map",
+      "sourceMapIsValid": false
+    },
     {
       "name": "rangeMappingsOutOfRange",
       "description": "Test an invalid range mapping which is outside the mappings length",
diff --git a/resources/proposals/range-mappings/invalid-vlq-zero.js b/resources/proposals/range-mappings/invalid-vlq-zero.js
new file mode 100644
index 0000000..c19bce9
--- /dev/null
+++ b/resources/proposals/range-mappings/invalid-vlq-zero.js
@@ -0,0 +1 @@
+//# sourceMappingURL=invalid-vlq-zero.js.map
diff --git a/resources/proposals/range-mappings/invalid-vlq-zero.js.map b/resources/proposals/range-mappings/invalid-vlq-zero.js.map
new file mode 100644
index 0000000..fe13e8f
--- /dev/null
+++ b/resources/proposals/range-mappings/invalid-vlq-zero.js.map
@@ -0,0 +1,9 @@
+{
+  "version": 3,
+  "names": [],
+  "file": "invalid-vlq-zero.js",
+  "sources": ["empty-original.js"],
+  "sourcesContent": [""],
+  "mappings": "A",
+  "rangeMappings": "A"
+}
diff --git a/resources/proposals/range-mappings/multiple-mappings.js.map b/resources/proposals/range-mappings/multiple-mappings.js.map
index 2fab6bd..c7ffc83 100644
--- a/resources/proposals/range-mappings/multiple-mappings.js.map
+++ b/resources/proposals/range-mappings/multiple-mappings.js.map
@@ -4,5 +4,5 @@
   "sources": ["multiple-mappings-original.js"],
   "sourcesContent": ["\"Hello World\";  function f() {   }  "],
   "mappings": ";CAAA,aAAa,EAAG,iBAAoB;A",
-  "rangeMappings": ";AC;"
+  "rangeMappings": ";BC;"
 }
diff --git a/resources/proposals/range-mappings/newline-semantics.js.map b/resources/proposals/range-mappings/newline-semantics.js.map
index 9f9e581..b6f7b44 100644
--- a/resources/proposals/range-mappings/newline-semantics.js.map
+++ b/resources/proposals/range-mappings/newline-semantics.js.map
@@ -5,5 +5,5 @@
   "sources": ["newline-semantics-original.js"],
   "sourcesContent": ["1234\n5678"],
   "mappings": "CAAA;GACG",
-  "rangeMappings": "A;"
+  "rangeMappings": "B;"
 }
diff --git a/resources/proposals/range-mappings/non-full-line-coverage.js.map b/resources/proposals/range-mappings/non-full-line-coverage.js.map
index a381b12..952a3c3 100644
--- a/resources/proposals/range-mappings/non-full-line-coverage.js.map
+++ b/resources/proposals/range-mappings/non-full-line-coverage.js.map
@@ -5,5 +5,5 @@
   "sources": ["simple-original.js"],
   "sourcesContent": ["\"Hello World\""],
   "mappings": ";CAAA;A",
-  "rangeMappings": ";A"
+  "rangeMappings": ";B"
 }
diff --git a/resources/proposals/range-mappings/out-of-range-2.js.map b/resources/proposals/range-mappings/out-of-range-2.js.map
index 152fd66..f573e03 100644
--- a/resources/proposals/range-mappings/out-of-range-2.js.map
+++ b/resources/proposals/range-mappings/out-of-range-2.js.map
@@ -5,5 +5,5 @@
   "sources": ["foo.js"],
   "sourcesContent": ["\"foo\""],
   "mappings": "AAA",
-  "rangeMappings": "B;A;A"
+  "rangeMappings": "C;B;B"
 }
diff --git a/resources/proposals/range-mappings/out-of-range.js.map b/resources/proposals/range-mappings/out-of-range.js.map
index 5ad9a23..5da575a 100644
--- a/resources/proposals/range-mappings/out-of-range.js.map
+++ b/resources/proposals/range-mappings/out-of-range.js.map
@@ -5,5 +5,5 @@
   "sources": ["foo.js"],
   "sourcesContent": ["\"foo\""],
   "mappings": "AAA",
-  "rangeMappings": "B"
+  "rangeMappings": "C"
 }
diff --git a/resources/proposals/range-mappings/simple.js.map b/resources/proposals/range-mappings/simple.js.map
index 0cd782b..856d31a 100644
--- a/resources/proposals/range-mappings/simple.js.map
+++ b/resources/proposals/range-mappings/simple.js.map
@@ -5,5 +5,5 @@
   "sources": ["simple-original.js"],
   "sourcesContent": ["\"Hello World\""],
   "mappings": ";CAAA;A",
-  "rangeMappings": ";A;"
+  "rangeMappings": ";B;"
 }