diff --git a/src/input/readers/Ascii.cc b/src/input/readers/Ascii.cc
index 4bf82c6a13..1923532103 100644
--- a/src/input/readers/Ascii.cc
+++ b/src/input/readers/Ascii.cc
@@ -11,6 +11,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
+#include <errno.h>
 
 using namespace input::reader;
 using threading::Value;
@@ -209,6 +210,34 @@ bool Ascii::GetLine(string& str)
 	return false;
 	}
 
+bool Ascii::CheckNumberError(const string & s, const char * end)
+	{
+
+	if ( s.length() == 0 )
+		{
+		Error("Got empty string for number field");
+		return true;
+		}
+
+	if ( end == s.c_str() ) {
+		Error(Fmt("String '%s' contained no parseable number", s.c_str()));
+		return true;
+	}
+
+	if ( *end != '\0' )
+		Error(Fmt("Number '%s' contained non-numeric trailing characters. Ignored trailing characters '%s'", s.c_str(), end));
+
+	if ( errno == EINVAL )
+		{
+		Error(Fmt("String '%s' could not be converted to a number", s.c_str()));
+		return true;
+		}
+	else if ( errno == ERANGE ) 
+		Error(Fmt("Number '%s' out of supported range. Number was truncated", s.c_str()));
+
+	return false;
+	}
+
 
 Value* Ascii::EntryToVal(string s, FieldMapping field)
 	{
@@ -216,6 +245,8 @@ Value* Ascii::EntryToVal(string s, FieldMapping field)
 		return new Value(field.type, false);
 
 	Value* val = new Value(field.type, true);
+	char* end;
+	errno = 0;
 
 	switch ( field.type ) {
 	case TYPE_ENUM:
@@ -239,22 +270,31 @@ Value* Ascii::EntryToVal(string s, FieldMapping field)
 		break;
 
 	case TYPE_INT:
-		val->val.int_val = strtoll(s.c_str(), (char**) NULL, 10);
+		val->val.int_val = strtoll(s.c_str(), &end, 10);
+		if ( CheckNumberError(s, end) ) 
+			return 0;
 		break;
 
 	case TYPE_DOUBLE:
 	case TYPE_TIME:
 	case TYPE_INTERVAL:
-		val->val.double_val = atof(s.c_str());
+		val->val.double_val = strtod(s.c_str(), &end);
+		if ( CheckNumberError(s, end) ) 
+			return 0;
 		break;
 
 	case TYPE_COUNT:
 	case TYPE_COUNTER:
-		val->val.uint_val = strtoull(s.c_str(),(char**) NULL, 10);
+		val->val.uint_val = strtoull(s.c_str(), &end, 10);
+		if ( CheckNumberError(s, end) ) 
+			return 0;
 		break;
-
+		
 	case TYPE_PORT:
-		val->val.port_val.port = atoi(s.c_str());
+		val->val.port_val.port = strtoull(s.c_str(), &end, 10);
+		if ( CheckNumberError(s, end) ) 
+			return 0;
+
 		val->val.port_val.proto = TRANSPORT_UNKNOWN;
 		break;
 
@@ -268,8 +308,11 @@ Value* Ascii::EntryToVal(string s, FieldMapping field)
 			return 0;
 			}
 
-		int width = atoi(s.substr(pos+1).c_str());
+		uint8_t width = (uint8_t) strtol(s.substr(pos+1).c_str(), &end, 10);
 		string addr = s.substr(0, pos);
+		
+		if ( CheckNumberError(s, end) ) 
+			return 0;
 
 		val->val.subnet_val.prefix = StringToAddr(addr);
 		val->val.subnet_val.length = width;
@@ -490,7 +533,7 @@ bool Ascii::DoUpdate()
 			Value* val = EntryToVal(stringfields[(*fit).position], *fit);
 			if ( val == 0 )
 				{
-				Error("Could not convert String value to Val");
+				Error(Fmt("Could not convert line '%s' to Val. Aborting file read.", line.c_str()));
 				return false;
 				}
 
diff --git a/src/input/readers/Ascii.h b/src/input/readers/Ascii.h
index e1506cbe82..2228e491b0 100644
--- a/src/input/readers/Ascii.h
+++ b/src/input/readers/Ascii.h
@@ -48,6 +48,7 @@ private:
 	bool ReadHeader(bool useCached);
 	bool GetLine(string& str);
 	threading::Value* EntryToVal(string s, FieldMapping type);
+	bool CheckNumberError(const string & s, const char * end);
 
 	ifstream* file;
 	time_t mtime;
diff --git a/testing/btest/Baseline/scripts.base.frameworks.input.bignumber/out b/testing/btest/Baseline/scripts.base.frameworks.input.bignumber/out
index ab095ca36c..8b95ed8b19 100644
--- a/testing/btest/Baseline/scripts.base.frameworks.input.bignumber/out
+++ b/testing/btest/Baseline/scripts.base.frameworks.input.bignumber/out
@@ -1,3 +1,4 @@
 {
-[9223372036854775800] = [c=18446744073709551612]
+[9223372036854775800] = [c=18446744073709551612],
+[-9223372036854775800] = [c=18446744073709551612]
 }
diff --git a/testing/btest/Baseline/scripts.base.frameworks.input.invalidnumbers/.stderrwithoutfirstline b/testing/btest/Baseline/scripts.base.frameworks.input.invalidnumbers/.stderrwithoutfirstline
new file mode 100644
index 0000000000..bd32495a6f
--- /dev/null
+++ b/testing/btest/Baseline/scripts.base.frameworks.input.invalidnumbers/.stderrwithoutfirstline
@@ -0,0 +1,8 @@
+error: ../input.log/Input::READER_ASCII: Number '12129223372036854775800' out of supported range. Number was truncated
+error: ../input.log/Input::READER_ASCII: Number '121218446744073709551612' out of supported range. Number was truncated
+error: ../input.log/Input::READER_ASCII: Number '9223372036854775801TEXTHERE' contained non-numeric trailing characters. Ignored trailing characters 'TEXTHERE'
+error: ../input.log/Input::READER_ASCII: Number '1Justtext' contained non-numeric trailing characters. Ignored trailing characters 'Justtext'
+error: ../input2.log/Input::READER_ASCII: String 'Justtext' contained no parseable number
+error: ../input2.log/Input::READER_ASCII: Could not convert line 'Justtext	1' to Val. Aborting file read.
+received termination signal
+>>>
diff --git a/testing/btest/Baseline/scripts.base.frameworks.input.invalidnumbers/out b/testing/btest/Baseline/scripts.base.frameworks.input.invalidnumbers/out
new file mode 100644
index 0000000000..9be82c13a9
--- /dev/null
+++ b/testing/btest/Baseline/scripts.base.frameworks.input.invalidnumbers/out
@@ -0,0 +1,5 @@
+{
+[9223372036854775807] = [c=18446744073709551615],
+[9223372036854775800] = [c=4],
+[9223372036854775801] = [c=1]
+}
diff --git a/testing/btest/scripts/base/frameworks/input/bignumber.bro b/testing/btest/scripts/base/frameworks/input/bignumber.bro
index 519992be05..250f84bbb2 100644
--- a/testing/btest/scripts/base/frameworks/input/bignumber.bro
+++ b/testing/btest/scripts/base/frameworks/input/bignumber.bro
@@ -10,6 +10,7 @@
 #fields	i	c
 #types	int	count
 9223372036854775800	18446744073709551612
+-9223372036854775800	18446744073709551612
 @TEST-END-FILE
 
 @load frameworks/communication/listen
diff --git a/testing/btest/scripts/base/frameworks/input/invalidnumbers.bro b/testing/btest/scripts/base/frameworks/input/invalidnumbers.bro
new file mode 100644
index 0000000000..7914b53d94
--- /dev/null
+++ b/testing/btest/scripts/base/frameworks/input/invalidnumbers.bro
@@ -0,0 +1,55 @@
+# (uses listen.bro just to ensure input sources are more reliably fully-read).
+# @TEST-SERIALIZE: comm
+#
+# @TEST-EXEC: btest-bg-run bro bro -b %INPUT
+# @TEST-EXEC: btest-bg-wait -k 5
+# @TEST-EXEC: btest-diff out
+# @TEST-EXEC: sed 1d .stderr > .stderrwithoutfirstline
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff .stderrwithoutfirstline
+
+@TEST-START-FILE input.log
+#separator \x09
+#fields	i	c
+#types	int	count
+12129223372036854775800	121218446744073709551612
+9223372036854775801TEXTHERE	1Justtext
+9223372036854775800	-18446744073709551612
+@TEST-END-FILE
+
+@TEST-START-FILE input2.log
+#separator \x09
+#fields	i	c
+#types	int	count
+Justtext	1
+@TEST-END-FILE
+
+
+@load frameworks/communication/listen
+
+global outfile: file;
+
+module A;
+
+type Idx: record {
+	i: int;
+};
+
+type Val: record {
+	c: count;
+};
+
+global servers: table[int] of Val = table();
+
+event bro_init()
+	{
+	outfile = open("../out");
+	# first read in the old stuff into the table...
+	Input::add_table([$source="../input.log", $name="ssh", $idx=Idx, $val=Val, $destination=servers]);
+	Input::remove("ssh");
+	}
+
+event Input::update_finished(name: string, source:string)
+	{
+	print outfile, servers;
+	Input::add_table([$source="../input2.log", $name="ssh2", $idx=Idx, $val=Val, $destination=servers]);
+	}