diff --git a/glslang/Include/revision.h b/glslang/Include/revision.h
index 3d25628c..a0a39d2e 100644
--- a/glslang/Include/revision.h
+++ b/glslang/Include/revision.h
@@ -9,5 +9,5 @@
 // source have to figure out how to create revision.h just to get a build
 // going.  However, if it is not updated, it can be a version behind.
 
-#define GLSLANG_REVISION "25411"
-#define GLSLANG_DATE     "2014/02/18 19:47:20"
+#define GLSLANG_REVISION "25511"
+#define GLSLANG_DATE     "2014/02/24 14:16:19"
diff --git a/glslang/MachineIndependent/PoolAlloc.cpp b/glslang/MachineIndependent/PoolAlloc.cpp
index 75c4972d..26b371ae 100644
--- a/glslang/MachineIndependent/PoolAlloc.cpp
+++ b/glslang/MachineIndependent/PoolAlloc.cpp
@@ -185,6 +185,7 @@ const unsigned char TAllocation::userDataFill       = 0xcd;
 //
 void TAllocation::checkGuardBlock(unsigned char* blockMem, unsigned char val, const char* locText) const
 {
+#ifdef GUARD_BLOCKS
     for (int x = 0; x < guardBlockSize; x++) {
         if (blockMem[x] != val) {
 			const int maxSize = 80;
@@ -196,6 +197,9 @@ void TAllocation::checkGuardBlock(unsigned char* blockMem, unsigned char val, co
             assert(0 && "PoolAlloc: Damage in guard block");
         }
     }
+#else
+    assert(guardBlockSize == 0);
+#endif
 }
 
 
diff --git a/glslang/MachineIndependent/Scan.h b/glslang/MachineIndependent/Scan.h
index 8f6e9e48..6a8d0ff0 100644
--- a/glslang/MachineIndependent/Scan.h
+++ b/glslang/MachineIndependent/Scan.h
@@ -93,9 +93,11 @@ public:
             do {
                 --currentSource;
             } while (currentSource > 0 && lengths[currentSource] == 0);
-            currentChar = lengths[currentSource] - 1;
-            if (currentChar < 0)
+            if (lengths[currentSource] == 0) {
+                // set to 0 if we've backed up to the start of an empty string
                 currentChar = 0;
+            } else
+                currentChar = lengths[currentSource] - 1;
         }
         if (peek() == '\n')
             --loc[currentSource].line;