diff --git a/glslang/MachineIndependent/ParseHelper.h b/glslang/MachineIndependent/ParseHelper.h
index e537ec62..83d0d563 100644
--- a/glslang/MachineIndependent/ParseHelper.h
+++ b/glslang/MachineIndependent/ParseHelper.h
@@ -218,6 +218,7 @@ public:
     void setCurrentSourceName(const char* name) { currentScanner->setFile(name); }
     void setCurrentString(int string) { currentScanner->setString(string); }
     void setScanner(TInputScanner* scanner) { currentScanner  = scanner; }
+    TInputScanner* getScanner() const { return currentScanner; }
 
     bool lineDirectiveShouldSetNextLine() const;
 
diff --git a/glslang/MachineIndependent/preprocessor/Pp.cpp b/glslang/MachineIndependent/preprocessor/Pp.cpp
index c17004b6..8e58a8c2 100644
--- a/glslang/MachineIndependent/preprocessor/Pp.cpp
+++ b/glslang/MachineIndependent/preprocessor/Pp.cpp
@@ -615,7 +615,7 @@ int TPpContext::CPPinclude(TPpToken* ppToken)
             bool success;
             std::tie(success, replacement) = includer.include(name);
             if (success) {
-                pushInput(new TokenizableString(replacement, this));
+                pushInput(new TokenizableString(directiveLoc, replacement, this));
                 // At EOF, there's no "current" location anymore.
                 if (token != EndOfInput) parseContext.setCurrentColumn(0);
                 // Don't accidentally return EndOfInput, which will end all preprocessing.
diff --git a/glslang/MachineIndependent/preprocessor/PpContext.h b/glslang/MachineIndependent/preprocessor/PpContext.h
index 82564ebc..5d06e701 100644
--- a/glslang/MachineIndependent/preprocessor/PpContext.h
+++ b/glslang/MachineIndependent/preprocessor/PpContext.h
@@ -134,6 +134,10 @@ public:
         virtual int getch() = 0;
         virtual void ungetch() = 0;
 
+        // Will be called when we start reading tokens from this instance
+        virtual void notifyActivated() {}
+        // Will be called when we do not read tokens from this instance anymore
+        virtual void notifyDeleted() {}
     protected:
         bool done;
         TPpContext* pp;
@@ -144,9 +148,11 @@ public:
     void pushInput(tInput* in)
     {
         inputStack.push_back(in);
+        in->notifyActivated();
     }
     void popInput()
     {
+        inputStack.back()->notifyDeleted();
         delete inputStack.back();
         inputStack.pop_back();
     }
@@ -426,19 +432,31 @@ protected:
     class TokenizableString : public tInput {
     public:
         // Copies str, which must be non-empty.
-        TokenizableString(const std::string& str, TPpContext* pp)
+        TokenizableString(const TSourceLoc& startLoc, const std::string& str, TPpContext* pp)
             : tInput(pp),
               str_(str),
               strings(str_.data()),
               length(str_.size()),
               scanner(1, &strings, &length),
-              stringInput(pp, scanner) {}
+              prevScanner(nullptr),
+              stringInput(pp, scanner) {
+                  scanner.setLine(startLoc.line);
+                  scanner.setString(startLoc.string);
+                  scanner.setFile(startLoc.name);
+        }
 
         // tInput methods:
         int scan(TPpToken* t) override { return stringInput.scan(t); }
         int getch() override { return stringInput.getch(); }
         void ungetch() override { stringInput.ungetch(); }
 
+        void notifyActivated() override
+        {
+            prevScanner = pp->parseContext.getScanner();
+            pp->parseContext.setScanner(&scanner);
+        }
+        void notifyDeleted() override { pp->parseContext.setScanner(prevScanner); }
+
     private:
         // Stores the titular string.
         const std::string str_;
@@ -448,6 +466,9 @@ protected:
         size_t length;
         // Scans over str_.
         TInputScanner scanner;
+        // The previous effective scanner before the scanner in this instance
+        // has been activated.
+        TInputScanner* prevScanner;
         // Delegate object implementing the tInput interface.
         tStringInput stringInput;
     };