diff --git a/src/sys/nact_sys1.cpp b/src/sys/nact_sys1.cpp
index aeb10e4..8f77318 100644
--- a/src/sys/nact_sys1.cpp
+++ b/src/sys/nact_sys1.cpp
@@ -1362,7 +1362,7 @@ uint16 NACT_Sys1::cali()
 		}
 	}
 	if (!ok) {
-		fatal("cali: invalid expression");
+		fatal("cali: invalid expression at %d:%04x", scenario_page, scenario_addr);
 	}
 	return (uint16)(cali[1] & 0xffff);
 }
@@ -1377,10 +1377,10 @@ uint16 NACT_Sys1::cali2()
 	} else if(0xc0 <= dat && dat <= 0xff) {
 		val = ((dat & 0x3f) << 8) | getd();
 	} else {
-		fatal("cali2: invalid expression");
+		fatal("cali2: invalid expression at %d:%04x", scenario_page, scenario_addr);
 	}
 	if(getd() != 0x7f) {
-		fatal("cali2: invalid expression");
+		fatal("cali2: invalid expression at %d:%04x", scenario_page, scenario_addr);
 	}
 	return val;
 }
diff --git a/src/sys/nact_sys2.cpp b/src/sys/nact_sys2.cpp
index 6b6460c..9625f4f 100644
--- a/src/sys/nact_sys2.cpp
+++ b/src/sys/nact_sys2.cpp
@@ -1342,7 +1342,7 @@ uint16 NACT_Sys2::cali()
 		}
 	}
 	if (!ok) {
-		fatal("cali: invalid expression");
+		fatal("cali: invalid expression at %d:%04x", scenario_page, scenario_addr);
 	}
 	return (uint16)(cali[1] & 0xffff);
 }
@@ -1357,10 +1357,10 @@ uint16 NACT_Sys2::cali2()
 	} else if(0xc0 <= dat && dat <= 0xff) {
 		val = ((dat & 0x3f) << 8) | getd();
 	} else {
-		fatal("cali2: invalid expression");
+		fatal("cali2: invalid expression at %d:%04x", scenario_page, scenario_addr);
 	}
 	if(getd() != 0x7f) {
-		fatal("cali2: invalid expression");
+		fatal("cali2: invalid expression at %d:%04x", scenario_page, scenario_addr);
 	}
 	return val;
 }
diff --git a/src/sys/nact_sys3.cpp b/src/sys/nact_sys3.cpp
index 5f71800..acfe978 100644
--- a/src/sys/nact_sys3.cpp
+++ b/src/sys/nact_sys3.cpp
@@ -1501,7 +1501,7 @@ uint16 NACT_Sys3::cali()
 		}
 	}
 	if (!ok) {
-		fatal("cali: invalid expression");
+		fatal("cali: invalid expression at %d:%04x", scenario_page, scenario_addr);
 	}
 	return (uint16)(cali[1] & 0xffff);
 }
@@ -1516,10 +1516,10 @@ uint16 NACT_Sys3::cali2()
 	} else if(0xc0 <= dat && dat <= 0xff) {
 		val = ((dat & 0x3f) << 8) | getd();
 	} else {
-		fatal("cali2: invalid expression");
+		fatal("cali2: invalid expression at %d:%04x", scenario_page, scenario_addr);
 	}
 	if(getd() != 0x7f) {
-		fatal("cali2: invalid expression");
+		fatal("cali2: invalid expression at %d:%04x", scenario_page, scenario_addr);
 	}
 	return val;
 }