diff --git a/src/__tests__/index.js b/src/__tests__/index.js
index 82fc839..9f9e2af 100644
--- a/src/__tests__/index.js
+++ b/src/__tests__/index.js
@@ -890,6 +890,15 @@ test(
   testValue('calc(1px + 2unknown)', 'calc(1px + 2unknown)')
 );
 
+test('decimal unknown units', async () => {
+  const result = await postcss(reduceCalc()).process(
+    'p{width: calc(120rpx - 41.7rpx)}',
+    postcssOpts
+  );
+  const warnings = result.warnings();
+  assert.is(warnings.length, 0);
+});
+
 test(
   'error with parsing',
   testThrows(
diff --git a/src/parser.jison b/src/parser.jison
index 90f57cd..462cd29 100644
--- a/src/parser.jison
+++ b/src/parser.jison
@@ -44,7 +44,7 @@
 (([0-9]+("."[0-9]+)?|"."[0-9]+)(e(\+|-)[0-9]+)?)dpcm\b            return 'RES';
 (([0-9]+("."[0-9]+)?|"."[0-9]+)(e(\+|-)[0-9]+)?)dppx\b            return 'RES';
 (([0-9]+("."[0-9]+)?|"."[0-9]+)(e(\+|-)[0-9]+)?)\%                return 'PERCENTAGE';
-(([0-9]+("."[0-9]+)?|"."[0-9]+)(e(\+|-)[0-9]+)?)\b                return 'NUMBER';
+(([0-9]+("."[0-9]+)?|"."[0-9]+)(e(\+|-)[0-9]+)?)(?!".")\b         return 'NUMBER';
 
 (([0-9]+("."[0-9]+)?|"."[0-9]+)(e(\+|-)[0-9]+)?)-?([a-zA-Z_]|[\240-\377]|(\\[0-9a-fA-F]{1,6}(\r\n|[ \t\r\n\f])?|\\[^\r\n\f0-9a-fA-F]))([a-zA-Z0-9_-]|[\240-\377]|(\\[0-9a-fA-F]{1,6}(\r\n|[ \t\r\n\f])?|\\[^\r\n\f0-9a-fA-F]))*\b       return 'UNKNOWN_DIMENSION';