diff --git a/assemble.c b/assemble.c
index 40fd80c..e161247 100644
--- a/assemble.c
+++ b/assemble.c
@@ -47,6 +47,10 @@ static int assemble(
     if (line == NULL)
         return -1;                     /* Return code for EOF. */
 
+    if (!enabl_lc) {                   /* If lower case disabled, */
+        upcase(line);                  /* turn it into upper case. */
+    }
+
     cp = line;
 
     /* Frankly, I don't need to keep "line."  But I found it quite
@@ -677,8 +681,11 @@ static int assemble(
                         else if (strcmp(label, "LSB") == 0) {
                             enabl_lsb = 1;
                             lsb = get_next_lsb();
-                        } else if (strcmp(label, "GBL") == 0)
+                        } else if (strcmp(label, "GBL") == 0) {
                             enabl_gbl = 1;
+                        } else if (strcmp(label, "LC") == 0) {
+                            enabl_lc = 1;
+                        }
                         free(label);
                         cp = skipdelim(cp);
                     }
@@ -693,8 +700,11 @@ static int assemble(
                         else if (strcmp(label, "LSB") == 0) {
                             lsb = get_next_lsb();
                             enabl_lsb = 0;
-                        } else if (strcmp(label, "GBL") == 0)
+                        } else if (strcmp(label, "GBL") == 0) {
                             enabl_gbl = 0;
+                        } else if (strcmp(label, "LC") == 0) {
+                            enabl_lc = 0;
+                        }
                         free(label);
                         cp = skipdelim(cp);
                     }
diff --git a/assemble_globals.c b/assemble_globals.c
index e7c1b4a..509797a 100644
--- a/assemble_globals.c
+++ b/assemble_globals.c
@@ -33,6 +33,8 @@ int             enabl_lsb = 0;  /* When set, stops non-local symbol
 
 int             enabl_gbl = 1;  /* Implicit definition of global symbols */
 
+int             enabl_lc = 1;   /* If lowercase disabled, convert assembler
+                                   source to upper case. */
 
 int             suppressed = 0; /* Assembly suppressed by failed conditional */
 
diff --git a/assemble_globals.h b/assemble_globals.h
index 63fc0c7..372fd53 100644
--- a/assemble_globals.h
+++ b/assemble_globals.h
@@ -46,6 +46,8 @@ extern int      enabl_lsb;      /* When set, stops non-local symbol
 
 extern int      enabl_gbl;      /* Implicit definition of global symbols */
 
+extern int      enabl_lc;       /* If lowercase disabled, convert assembler
+                                   source to upper case. */
 extern int      suppressed;     /* Assembly suppressed by failed conditional */
 
 extern MLB     *mlbs[MAX_MLBS]; /* macro libraries specified on the command line */