diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CompleteParseASTTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CompleteParseASTTest.java
index 281a6be4e1f..b5724cb6ec2 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CompleteParseASTTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/CompleteParseASTTest.java
@@ -2480,5 +2480,23 @@ public class CompleteParseASTTest extends CompleteParseBaseTest
     	IASTVariable pBase = (IASTVariable)i.next();
     	assertEquals(pBase.getStartingLine(), 19);
     }
+    
+    public void testBug79471() throws Exception {
+    	Writer writer = new StringWriter();
+    	writer.write("void testFloatAccess(float * fp) {\n"); //$NON-NLS-1$
+    	writer.write("#define VAL 2.0f\n"); //$NON-NLS-1$
+    	writer.write("if(*fp > VAL) { /* Syntax error is here */\n}\n}\n"); //$NON-NLS-1$
+    	parse(writer.toString());
+    	writer = new StringWriter();
+    	writer.write("void testFloatAccess(float * fp) {\n"); //$NON-NLS-1$
+    	writer.write("#define VAL 2.0l\n"); //$NON-NLS-1$
+    	writer.write("if(*fp > VAL) { /* Syntax error is here */\n}\n}\n"); //$NON-NLS-1$
+    	parse(writer.toString());
+    	writer = new StringWriter();
+    	writer.write("void testFloatAccess(float * fp) {\n"); //$NON-NLS-1$
+    	writer.write("#define VAL 2.0f\n"); //$NON-NLS-1$
+    	writer.write("if(VAL > VAL) { /* Syntax error is here */\n}\n}\n"); //$NON-NLS-1$
+    	parse(writer.toString());
+    }
 }
 
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner2/Scanner2.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner2/Scanner2.java
index 36e07ee5743..a6d7a93b080 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner2/Scanner2.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/parser/scanner2/Scanner2.java
@@ -1328,7 +1328,7 @@ public class Scanner2 implements IScanner, IScannerData {
 					// must be float suffix
 					++bufferPos[bufferStackPos];
 
-					if (buffer[bufferPos[bufferStackPos]] == 'i')
+					if (bufferPos[bufferStackPos] < buffer.length && buffer[bufferPos[bufferStackPos]] == 'i')
 						continue; // handle GCC extension 5.10 Complex Numbers 
 
 					break; // fix for 77281 (used to be continue)