diff --git a/stdscan.c b/stdscan.c
index 3979144e..c2f97e80 100644
--- a/stdscan.c
+++ b/stdscan.c
@@ -118,6 +118,8 @@ int stdscan(void *private_data, struct tokenval *tv)
         bool rn_error;
 	bool is_hex = false;
 	bool is_float = false;
+	bool has_e = false;
+	bool has_h = false;
 	char c;
 
         r = stdscan_bufptr++;
@@ -128,8 +130,17 @@ int stdscan(void *private_data, struct tokenval *tv)
 	for (;;) {
 	    c = *stdscan_bufptr++;
 
-	    if ((!is_hex && (c == 'e' || c == 'E')) ||
-		(c == 'P' || c == 'p')) {
+	    if (!is_hex && (c == 'e' || c == 'E')) {
+		has_e = true;
+		if (*stdscan_bufptr == '+' || *stdscan_bufptr == '-') {
+		    /* e can only be followed by +/- if it is either a
+		       prefixed hex number or a floating-point number */
+		    is_float = true;
+		    stdscan_bufptr++;
+		}
+	    } else if (c == 'H' || c == 'h') {
+		has_h = true;
+	    } else if (c == 'P' || c == 'p') {
 		is_float = true;
 		if (*stdscan_bufptr == '+' || *stdscan_bufptr == '-')
 		    stdscan_bufptr++;
@@ -142,6 +153,11 @@ int stdscan(void *private_data, struct tokenval *tv)
 	}
 	stdscan_bufptr--;	/* Point to first character beyond number */
 
+	if (has_e && !has_h) {
+	    /* 1e13 is floating-point, but 1e13h is not */
+	    is_float = true;
+	}
+
 	if (is_float) {
 	    tv->t_charptr = stdscan_copy(r, stdscan_bufptr - r);
 	    return tv->t_type = TOKEN_FLOAT;
@@ -154,7 +170,8 @@ int stdscan(void *private_data, struct tokenval *tv)
 	    tv->t_charptr = NULL;
 	    return tv->t_type = TOKEN_NUM;
 	}
-    } else if (*stdscan_bufptr == '\'' || *stdscan_bufptr == '"') {     /* a char constant */
+    } else if (*stdscan_bufptr == '\'' || *stdscan_bufptr == '"') {
+	/* a char constant */
         char quote = *stdscan_bufptr++, *r;
         bool rn_warn;
         r = tv->t_charptr = stdscan_bufptr;
diff --git a/test/uscore.asm b/test/uscore.asm
index 6cb99ea3..2bc99c25 100644
--- a/test/uscore.asm
+++ b/test/uscore.asm
@@ -1,6 +1,10 @@
 	dd 0x1234_5678
 	dd 305_419_896		; Same number as above it
 	dd 0x1e16		; NOT a floating-point number!
+	dd 1e16h		; NOT a floating-point number!
+	dd 1e16_h		; NOT a floating-point number!
+	dd $1e16		; NOT a floating-point number!
+	dd $1e16		; NOT a floating-point number!
 	dd 1e16			; THIS is a floating-point number!
 	dd 1e+16
 	dd 1.e+16