diff --git a/clang-tools-extra/clangd/Selection.cpp b/clang-tools-extra/clangd/Selection.cpp
--- a/clang-tools-extra/clangd/Selection.cpp
+++ b/clang-tools-extra/clangd/Selection.cpp
@@ -369,7 +369,8 @@
     //   }
     // Selecting "++x" or "x" will do the right thing.
     auto Range = toHalfOpenFileRange(SM, LangOpts, S);
-    assert(Range && "We should be able to get the File Range");
+    if(!Range)
+      return SelectionTree::Unselected;
     dlog("{1}claimRange: {0}", Range->printToString(SM), indent());
     auto B = SM.getDecomposedLoc(Range->getBegin());
     auto E = SM.getDecomposedLoc(Range->getEnd());
diff --git a/clang-tools-extra/clangd/SourceCode.cpp b/clang-tools-extra/clangd/SourceCode.cpp
--- a/clang-tools-extra/clangd/SourceCode.cpp
+++ b/clang-tools-extra/clangd/SourceCode.cpp
@@ -295,37 +295,63 @@
   return SourceRange(std::min(R1.getBegin(), R2.getBegin()),
                      E1 < E2 ? R2.getEnd() : R1.getEnd());
 }
-
-// Returns the tokenFileRange for a given Location as a Token Range
+// If Loc is a macro arg expansion, return the immediate spelling loc.
+// Otherwise 
+// Assumes Loc is in a macro file ID
+static SourceRange getExpansionOrSpellingRange(SourceLocation Loc,
+                                               const SourceManager &SM,
+                                               const LangOptions &LangOpts) {
+  if (SM.isMacroArgExpansion(Loc))
+    return SM.getImmediateSpellingLoc(Loc);
+  return toTokenRange(SM.getImmediateExpansionRange(Loc), SM, LangOpts);
+}
+
+// Returns the tokenFileRange for a given Range as a Token Range
 // This is quite similar to getFileLoc in SourceManager as both use
 // getImmediateExpansionRange and getImmediateSpellingLoc (for macro IDs).
 // However:
 // - We want to maintain the full range information as we move from one file to
 //   the next. getFileLoc only uses the BeginLoc of getImmediateExpansionRange.
-// - We want to split '>>' tokens as the lexer parses the '>>' in template
-//   instantiations as a '>>' instead of a '>'.
+// - We want to split '>>' tokens as the lexer parses the '>>' in nested
+// template instantiations as a '>>' instead of two '>'s.
 // There is also getExpansionRange but it simply calls
 // getImmediateExpansionRange on the begin and ends separately which is wrong.
-static SourceRange getTokenFileRange(SourceLocation Loc,
-                                     const SourceManager &SM,
+static SourceRange getTokenFileRange(SourceRange Rng, const SourceManager &SM,
                                      const LangOptions &LangOpts) {
-  SourceRange FileRange = Loc;
-  while (!FileRange.getBegin().isFileID()) {
-    assert(!FileRange.getEnd().isFileID() &&
-           "Both Begin and End should be MacroIDs.");
-    if (SM.isMacroArgExpansion(FileRange.getBegin())) {
-      FileRange.setBegin(SM.getImmediateSpellingLoc(FileRange.getBegin()));
-      FileRange.setEnd(SM.getImmediateSpellingLoc(FileRange.getEnd()));
-    } else {
-      SourceRange ExpansionRangeForBegin = toTokenRange(
-          SM.getImmediateExpansionRange(FileRange.getBegin()), SM, LangOpts);
-      SourceRange ExpansionRangeForEnd = toTokenRange(
-          SM.getImmediateExpansionRange(FileRange.getEnd()), SM, LangOpts);
-      FileRange = unionTokenRange(ExpansionRangeForBegin, ExpansionRangeForEnd,
-                                  SM, LangOpts);
-    }
+  // Map from FileID hash to SourceRange
+  std::map<unsigned, SourceRange> RngMap;
+  // Adds a Location to the RngMap
+  auto AddLocToMap = [&RngMap, &SM, &LangOpts](SourceLocation Loc) {
+    unsigned FileIDHash = SM.getFileID(Loc).getHashValue();
+    auto It = RngMap.find(FileIDHash);
+    if (It == RngMap.end())
+      RngMap[FileIDHash] = Loc;
+    else
+      It->second = unionTokenRange(It->second, Loc, SM, LangOpts);
+  };
+  auto AddRngToMap = [&](SourceRange SR) {
+    AddLocToMap(SR.getBegin());
+    AddLocToMap(SR.getEnd());
+  };
+  // Initialize RngMap
+  AddRngToMap(Rng);
+  // Iterate until only one range is left which is not a macroID
+  for (auto It = RngMap.rbegin();
+       !RngMap.empty() && It->second.getBegin().isMacroID();
+       It = RngMap.rbegin()) {
+    // Get SourceRange with maximum FileID and remove from RngMap
+    Rng = It->second;
+    RngMap.erase(It->first);
+    // Add Immediate Expansion/Spelling Range to RngMap
+    AddRngToMap(getExpansionOrSpellingRange(Rng.getBegin(), SM, LangOpts));
+    AddRngToMap(getExpansionOrSpellingRange(Rng.getEnd(), SM, LangOpts));
   }
-  return FileRange;
+  assert(RngMap.size() == 1 && "There should be only one final range.");
+  SourceRange TokenFileRange = RngMap.begin()->second;
+  assert(isInsideMainFile(TokenFileRange.getBegin(), SM) &&
+         isInsideMainFile(TokenFileRange.getBegin(), SM) &&
+         "Final range should be in main file.");
+  return TokenFileRange;
 }
 
 bool isInsideMainFile(SourceLocation Loc, const SourceManager &SM) {
@@ -335,15 +361,10 @@
 llvm::Optional<SourceRange> toHalfOpenFileRange(const SourceManager &SM,
                                                 const LangOptions &LangOpts,
                                                 SourceRange R) {
-  SourceRange R1 = getTokenFileRange(R.getBegin(), SM, LangOpts);
-  if (!isValidFileRange(SM, R1))
-    return llvm::None;
-
-  SourceRange R2 = getTokenFileRange(R.getEnd(), SM, LangOpts);
-  if (!isValidFileRange(SM, R2))
+  SourceRange Result = getTokenFileRange(R, SM, LangOpts);
+  if (!isValidFileRange(SM, Result))
     return llvm::None;
 
-  SourceRange Result = unionTokenRange(R1, R2, SM, LangOpts);
   unsigned TokLen = getTokenLengthAtLoc(Result.getEnd(), SM, LangOpts);
   // Convert from closed token range to half-open (char) range
   Result.setEnd(Result.getEnd().getLocWithOffset(TokLen));
diff --git a/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp b/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
--- a/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
@@ -460,15 +460,22 @@
     #define FOO(X, Y) int Y = ++X
     #define BAR(X) X + 1
     #define ECHO(X) X
+
+    #define BUZZ BAZZ(ADD)
+    #define BAZZ(m) m(1)
+    #define ADD(a) int f = a + 1;
     template<typename T>
     class P {};
-    void f() {
+
+    int main() {
       $a[[P<P<P<P<P<int>>>>> a]];
       $b[[int b = 1]];
       $c[[FOO(b, c)]]; 
       $d[[FOO(BAR(BAR(b)), d)]];
       // FIXME: We might want to select everything inside the outer ECHO.
       ECHO(ECHO($e[[int) ECHO(e]]));
+      // Shouldn't crash.
+      $f[[BUZZ]];
     }
   )cpp");
 
@@ -495,6 +502,7 @@
   CheckRange("c");
   CheckRange("d");
   CheckRange("e");
+  CheckRange("f");
 }
 
 } // namespace