diff --git a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/assembler/sleigh/grammars/AssemblySentential.java b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/assembler/sleigh/grammars/AssemblySentential.java
index b9a75abe7b..1a5388ddc8 100644
--- a/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/assembler/sleigh/grammars/AssemblySentential.java
+++ b/Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/app/plugin/assembler/sleigh/grammars/AssemblySentential.java
@@ -149,7 +149,7 @@ public class AssemblySentential<NT extends AssemblyNonTerminal> extends
 					return Collections.singleton(new WhiteSpaceParseToken(grammar, this, ""));
 				}
 				if (Character.isLetterOrDigit(buffer.charAt(b)) &&
-					Character.isLetterOrDigit(buffer.charAt(b - 1))) {
+					(b == 0 || Character.isLetterOrDigit(buffer.charAt(b - 1)))) {
 					return Collections.emptySet();
 				}
 			}