diff --git a/NEWS.md b/NEWS.md
index bb53a9b..4ddb742 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,7 @@
 # tidyxl 1.0.2
 
+* Correctly constructs formulas where references are preceded by operators, e.g.
+    `-F10` (#26 @cablegui).
 * No longer misinterprets date formats that use underscores `_` as dates when
     the underscore is followed by a date-ish character like `M` (#24).
 
diff --git a/src/ref_grammar.h b/src/ref_grammar.h
index 71231fe..dd5901e 100644
--- a/src/ref_grammar.h
+++ b/src/ref_grammar.h
@@ -23,6 +23,23 @@ namespace xlref
   struct openparen: one< '(' > {};
   struct closeparen: one< ')' > {};
 
+  // Operators
+  struct plusop : one< '+' > {};
+  struct minusop : one< '-' > {};
+  struct mulop : one< '*' > {};
+  struct divop : one< '/' > {};
+  struct expop : one< '^' > {};
+  struct concatop : one< '&' > {};
+  struct intersectop : one< ' ' > {};
+  struct rangeop : one< ':' > {};
+  struct percentop : one< '%' > {};
+  struct gtop : one< '>' > {};
+  struct eqop : one< '=' > {};
+  struct ltop : one< '<' > {};
+  struct neqop : string< '<', '>' > {};
+  struct gteop : string< '>', '=' > {};
+  struct lteop : string< '<', '=' > {};
+
   // Text matches two QuoteD (") and anything between, i.e. character and
   // the surrounding pair of double-quotes.
   struct QuoteD : one< '"' > {};
@@ -32,10 +49,27 @@ namespace xlref
   {};
   struct Text : seq< QuoteD, DoubleQuotedString, QuoteD > {};
 
+  struct Operator : sor< plusop,
+                         minusop,
+                         mulop,
+                         divop,
+                         expop,
+                         concatop,
+                         intersectop,
+                         rangeop,
+                         percentop,
+                         eqop,
+                         neqop, // Must precede lteop and ltop
+                         gteop, // Must precede gtop
+                         lteop, // Must precede ltop
+                         gtop,
+                         ltop >
+  {};
+
   // After attempting a Ref, attempt a Text, otherwise consume everything up to
-  // the next dollar, comma or parentheses, which are characters that separate
-  // other tokens.
-  struct sep: sor< dollar, comma, openparen, closeparen > {};
+  // the next operator, dollar, comma or parentheses, which are characters that
+  // separate other tokens.
+  struct sep: sor< Operator, dollar, comma, openparen, closeparen > {};
   struct notsep: if_then_else< at< sep >, failure, any > {};
   struct notseps: plus< notsep > {};
   struct Other: sor< sep, notseps > {};
diff --git a/tests/testthat/formulas.xlsx b/tests/testthat/formulas.xlsx
index 7eeaf01..62c64ed 100755
Binary files a/tests/testthat/formulas.xlsx and b/tests/testthat/formulas.xlsx differ
diff --git a/tests/testthat/test-shared-formula.R b/tests/testthat/test-shared-formula.R
index 18507bb..d165eb6 100644
--- a/tests/testthat/test-shared-formula.R
+++ b/tests/testthat/test-shared-formula.R
@@ -11,5 +11,5 @@ test_that("Shared formulas are propogated correctly", {
   expect_equal(formulas[239], "E09904.2!A3")
   formulas <- tidyxl::xlsx_cells("./formulas.xlsx")$formula
   expect_equal(formulas[3], "N($A2)")
+  expect_equal(formulas[12], "G4*H4")
 })
-